HomeMy WebLinkAboutR-2008-074 CFHM Plan; Upper Yakima River Comprehensive Flood Hazard Management PlanRESOLUTION NO. R-2008-74
A RESOLUTION of the City of Yakima, Washington, adopting the Upper Yakima
River Comprehensive Flood Hazard Management Plan RM 107-
128 June 2007 Update, Including New Appendix F.
WHEREAS, the Yakima Countywide Flood Control Zone District was formed in
1998 and prepared a Comprehensive Flood Hazard Management Plan in 1998; and
WHEREAS, in 2004 the 1998 plan was amended and updated; and
WHEREAS, the amended plan bearing the formal title "Upper Yakima River
Comprehensive Flood Hazard Management Plan RM 107-128" with amendment date of
June, 2007 (hereinafter "CFHMP"), was adopted by the Yakima County Board of
County Commissioners in Resolution No. 287-2007 dated June 19, 2007; and
WHEREAS, in some cases the contents of the CFHMP may overlap with the
contents of the City of Yakima Urban Area Comprehensive Plan 2025 (hereinafter "Plan
2025") and development regulations of the City of Yakima; and
WHEREAS, the CFHMP represents a valuable inter -governmental effort
regarding flood control for the relevant affected geographic areas; and
WHEREAS, the CFHMP should not constitute an additional layer of potentially
inconsistent policies or regulations binding on and within the City of Yakima, but should
instead serve, only as an advisory complement to other City of Yakima planning
endeavors, including Plan 2025 and the City of Yakima's development regulations; and
WHEREAS, in the event of any conflict between the CFHMP (including any
policy, rule, regulation, or requirement contained therein), and Plan 2025 or any of the
City of Yakima's development regulations, Plan 2025 and/or the City of Yakima's
development regulations should be deemed authoritative and controlling within the City
of Yakima for all purposes; and
WHEREAS, a new appendix (hereinafter "New Appendix F") should be included
with the CFHMP to address any such express or latent conflicts; and
WHEREAS, the Yakima City Council finds and determines that it is in the public
interest to adopt the resolution set forth herein;
NOW, THEREFORE, BE IT RESOLVED by the Council of the City of Yakima,
Washington:
The Upper Yakima River Comprehensive Flood Hazard Management Plan RM
107-128 June 2007 Update, Including New Appendix F, is adopted; provided, however,
that the CFHMP shall by this resolution be limited in effect solely to serving as an
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advisory complement to other City of Yakima planning endeavors, including Plan 2025
and the City of Yakima's development regulations; and provided, further, that in the
event of any conflict between the CFHMP (including any policy, rule, regulation, or
requirement contained therein), and Plan 2025 or any of the City of Yakima's
development regulations, Plan 2025 and/or the City of Yakima's development
regulations are and shall be deemed authoritative and controlling within the City of
Yakima for all purposes.
ADOPTED BY THE CITY COUNCIL this 6th day of May, 2008.
ATTEST:
David Edler, Mayor
/-az--A-0-1 rx 1 i
City Clerk(
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TO:
FROM:
SUBJECT:
MEMORANDUM
Honorable Mayor David Edler
Members of Yakima City Council
City Manager Dick Zais
City Attorney Ray Paolella
Kenneth W. Harper, outside legal counsel
Overview Regarding Adoption of Upper Yakima River
Comprehensive Flood Hazard Management Plan
DATE: April 24, 2008
I. INTRODUCTION
This memorandum provides an overview of the proposed adoption by the City of Yakima
of the Upper Yakima River Comprehensive Flood Hazard Management Plan RM 107-
128 June 2007 Update (referred to as the "CFHMP").
II. BACKGROUND OF CFHMP
The CFHMP was adopted by the Board of Yakima County Commissioners on June 19,
2007. It was produced at the direction of the Yakima Countywide Flood Control Zone
District, an independent taxing district authorized by state law and created by the Board
of Yakima County Commissioners on January 13, 1998.
The CFHMP primarily describes a coordinated approach to flood hazard management for
the Yakima River from the Yakima County northern boundary to Union Gap and along
the Naches River from Twin Bridges on SR 12 to its mouth. A copy of the executive
summary of the CFHMP is attached to this memorandum.
MEMORANDUM: Overview Regarding
Adoption of Upper Yakima Comprehensive
Flood Hazard Management Plan - 1
III. SIGNIFICANCE OF CFHMP TO THE CITY OF YAKIMA
As a statutorily -prescribed comprehensive flood control management plan, the CFHMP
will, upon adoption by the City of Yakima, become binding. RCW 86.12.210. Any land
use regulations and restrictions on construction activity contained within the CFHMP that
are applicable to the City of Yakima will become the minimum standards of the City and
may supplant existing City of Yakima regulations and standards.
A. Limitations on assessment of the effect of the CFHMP on the City's existing
regulations.
The CFHMP does not contain a clear statement of the regulations and restrictions
contained within the plan that are applicable to the City of Yakima. Much of the
CFHMP, in fact, is devoid of prescriptive content at the land use regulatory level.
Instead, most of the plan's chapters contain general descriptions of regional concerns
regarding flood damage protection, resource protection, and environmental enhancement
within the plan study area.
At Chapter Six, entitled "Regulations," the CFHMP provides an overview of existing
federal, state, and local regulatory and permitting requirements that relate to flood hazard
management, surface water management, water quality, and wetland protection.
It is unclear whether the CFHMP is intended solely to depict the relationship between
existing regulations and flood hazard management policies or, on the other hand, whether
the CFHMP is also intended to establish a foundation for mandatory future regulations.
Because the plan is unclear on this point, it is impossible to precisely identify what future
regulations the CFHMP may be intended to support or how the CFHMP may affect future
development regulation enforcement in the City of Yakima.
B. Ambiguity of CFHMP requirements for implementation of policies.
The CFHMP is ambiguous regarding the extent to which it establishes recommendations
or requirements for future project and non -project actions to implement its policies.
Chapter Eight of the CFHMP, entitled "Flood Mitigation Alternatives," lists thirty-three
separate "flooding issues" that appear to be set forth as recommended actions and policy
changes to reduce flood hazards within the plan's study area.
The CFHMP states that additional environmental review and comprehensive assessments
will be performed when specific projects may be proposed by proponents. Although this
representation indicates that project -level environmental review will be necessary before
project actions proceed, it is unclear whether adoption of the CFHMP commits the City
MEMORANDUM: Overview Regarding
Adoption of Upper Yakima Comprehensive
Flood Hazard Management Plan - 2
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of Yakima to policies geared toward the ultimate implementation of some or all of the
ranked "flooding issue" mitigation measures.
Several of the "flooding issues" are not project -specific, and the CFHMP is also unclear
regarding the expectation for future review and analysis of non -project "flooding issue"
mitigation measures, as well as the environmental review processes that would be
associated with each.
For each of the ranked "flooding issues," the CFHMP sets forth a preferred alternative
and recommended action statement. The preferred alternative and recommended actions
may or may not represent appropriate public policy for the City of Yakima and, likewise,
may or may not present insurmountable environmental review and assessment problems.
Thus, for instance, the preferred alternative and recommended action regarding critical
areas ordinance consistency states that "City jurisdictions should integrate flood hazard
items included in the County's CAO that are not specified in their respective FHOs or
CAOs or develop an interlocal agreement creating a FHO that applies across all
jurisdictional boundaries." (See CFHMP at 8-61). This language suggests that the City
of Yakima has an obligation to reconsider its recently -adopted critical areas ordinance for
consistency with respect to the integration of flood hazard items compared to the
County's critical area ordinance. No such formal analysis has been performed, and it is
unclear how this analysis would relate to questions of the City's sovereignty over its
CAO process.
Similarly, the CFHMP endorses as its "flood issue number one" the re -configuration of
the levee system adjacent to the Yakima Regional Wastewater Treatment Plant
(-WWTP"). (See CFHMP at 8-3). It is probable that alteration of the levee system will
affect the Yakima River's hydrology near the WWTP's outfall, with potentially dramatic
consequences to the viability of the current WWTP.
As summarized in the CFHMP:
Changes to the configuration of the bridge and levee
system upstream can be expected to change the hydraulic
conditions at the outfall, with a very high probability that
the river channel will begin to move/migrate if the levees
are relocated. This would potentially result in the outfall
no longer being located in the river, the outfall being buried
as the river recovers to a more natural elevation, or reduced
flow and turbulence at the outfall, any of which would
result in violation of water quality standards and/or the
City's NPDES permit from the Department of Ecology,
which allows the WWTP to discharge to the river. (See
CFHMP at 8-11).
MEMORANDUM: Overview Regarding
Adoption of Upper Yakima Comprehensive
Flood Hazard Management Plan - 3
At the time of this memorandum, there has been no formal assessment of the significance
of this change, including from an environmental, fiscal, or other public policy
perspective.
The proposed setback of the levee has the potential to significantly alter the course of the
river thereby impacting the WWTP outfall mixing zone. The impact of such a change
has not been fully evaluated as part of the CFHMP planning process. It will be necessary
that the environmental review efforts of future capital improvements undertaken to
implement the plan include a thorough analysis and mitigation of the impacts to the
WWTP outfall, which could be significant.
IV. CONCLUSION
Overall, the City's proposed adoption of the CFHMP brings with it risks that are difficult
to quantify. The risks identified above are not exclusive, in part because the CFHMP
itself contains ambiguities and also in part because the City (including the author of this
memorandum) does not have the ability to fully analyze the technical content of the plan.
Identified risks of adoption can, at this time, be summarized as follows:
• Inconsistency between CFHMP policies and regulations as compared to existing
City of Yakima policies and regulations;
• Ambiguity regarding the source of development regulation standards for land use
permitting activities within the City;
• Unclear relationship between independent assessment by the City of policy
choices regarding flood hazard management through City decision-making
processes and implementation of CFHMP-determined "flooding issues," both
project and non -project; and
• Establishment of expectation that City of Yakima critical areas and flood hazard
ordinances will be modified to achieve consistency with similar regulations of
Yakima County.
KWH:ksl
MEMORANDUM: Overview Regarding
Adoption of Upper Yakima Comprehensive
Flood Hazard Management Plan - 4
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EXECUTIVE SUMMARY
This 2007 plan is an update of the 1998 Upper Yakima River Comprehensive Flood Hazard
Management Plan (CFHIMIP) for the Yakima River from the Yakima County northern boundary
to Union Gap and along the Naches River from Twin Bridges on State Route 12 to its mouth.
The CFHMP is a policy document which contains recommended actions or policy changes to
reduce flood hazard in a comprehensive fashion. The CFHMP fulfills one of the main
requirements for the County to be eligible for funding from the State of Washington under the
Flood Control Assistance Account Program (FCAAP)
YAKIMA FLOODING HISTORY AND IMPACTS
Since 1894, the flow in the Yakima River has exceeded flood level 47 times Since 1970 the area
was declared a federal disaster area due to flooding 8 times in 27 years. The largest flood of
record occurred in December 1933, despite completion of the Yakima Project reservoir system
by the US Bureau of Reclamation.
In 1938 designs for a federal levee system on the Yakima River were completed, but this project
was not constructed until after World War II, completed in 1948, and repaired and extended the
next year after the 1948 flood. These works were constructed to protect the urban areas of
Yakima and Terrace Heights. A series of large floods during the 1970's prompted further
studies by the Corps, and the levees earlier constructed under Corps authority were raised
twice in the 1970's and the 1980's. The need for raising of the levees resulted from river channel
rise (aggradation) since construction of the federal project. The Wastewater Treatment Plant
Levee, built in 1958, has been reconstructed 8 times due to scour at the toe of the levee.
Most of the same floods occurred on the Naches River. In the 1970's, SR 12 was constructed
adjacent to the river, to an elevation to withstand the 200 year flood. The area of SR 12 upstream
of the 16th Avenue exit has experienced repeated flood damage since the 1980's and failure of
this roadway during a major flood event would inundate a significant portion of Yakima.
There were three major flood events in the 1990's culminating in the 1996 flood. During this
flood (approximately a 100 year flood), several areas along the Corps levees protecting the
urban area received successful emergency reinforcement during the flood, including:
• The west bank levee at Buchannan Lake (also known as the Beech Street Gravel
Pit)
• The east bank levee immediately downstream of Terrace Heights bridge
Failure at either of these locations would have resulted in widespread damages and inundation
of a large number of businesses and residences.
The following occurred at non -corps levee locations:
• Raising of the east bank Drainage Improvement District #1 levee immediately
downstream of SR -24 bridge to prevent overtopping and failure.
• Overtopping and damage to the west bank Waste Water Treatment Plant levee
located across from the DID #1 levee.
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Upper Yakima River Comprehensive FIood Hazard Management PIan
• Major failure of a private west bank levee in Selah that protected a large
floodplain gravel mining pit. Failure of that levee caused erosion of two lanes of
I-82, and the closure of I-82 during the flood event.
• Overtopping of, and damage to, I-82 near Union Gap
The ability of flood protection facilities to withstand erosion and overtopping by floodwaters is
a continuing concern. Countywide damage from the 1996 flood alone was 18 million dollars
The presence of numerous confining flood protection levees, and roads crossings that act as
levees in the planning area result in increased flood hazards due to their disruption of, and
increased exposure to, natural riverine processes. The active floodplain width has been reduced
to as little as one eighth its former width at several locations. The physical conditions in the
river channel change from year to year on a more rapid basis than before confinement, which
also changes flood effects exerted against the levees and other infrastructure, such as height of
flood waters, water velocity, and the location of erosive energy Expensive maintenance and
repairs are required to keep the levee system in place in order to reduce damages to businesses,
homes, roads, SR 24 , 1-82 and infrastructure such as irrigation, water, and wastewater systems.
At this time Yakima County has one of only two remaining Corps certified levee systems within
the state. This qualification enables technical and financial aid from the federal government.
The impacts of past floods, which threaten the levee system and result in millions of dollars of
damage, indicate the need for effective long term flood hazard management and planning
COMPREHENSIVE FLOOD HAZARD MANAGEMENT PLANNING
Since 1986 state financial assistance for flood control works has been under the authority of the
Revised Code of Washington (RCW) Chapter 86.26 and requires the development of a flood
management plan. Since 1991 this funding requires adoption of a plan development process in
accordance with the 1991 guidebook from Department of Ecology, entitled "Comprehensive
Planning for FIood Hazard Management". A management plan, so developed, is referred to as
a "Comprehensive Flood Hazard Management Plan (CFHMP)" and, upon approval by the
Department of Ecology, qualifies the agency for funding under Washington Administrative
Code (WAC) Chapter 173-145• Administration of the Flood Control Assistance Account
Program (FCAAP) State funds from this program can be used for emergency and non-
emergency activities that reduce property loss and threats to human health caused by flooding.
In addition, the CFHMP is recognized by the Federal Emergency Management Agency (FEMA)
and the Washington State Emergency Management Division as a mitigation plan to be used to
direct post -disaster mitigation measures
The CFHMP requires the following steps of the planning process
• Establish a citizen and agency participation process
• Set goals and objectives for flood hazard management
• Develop an inventory and analysis of physical conditions
• Determine the need for flood hazard management measures
• Review existing regulations that impact flood hazard management.
• Identity alternative flood hazard management measures
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. EXECUTIVE SUMMARY
• Evaluate alternative measures
• Hold Advisory Committee meetings for evaluation of alternatives
• Develop a flood hazard management strategy
• Complete the draft CFHMP and submit to Ecology
• Submit the final CFHMP to Ecology
• Hold a public hearing and adopt the CFHMP
• Notify Ecology the final plan is adopted.
1998 UPPER YAKIMA CFHMP
In response to the flood events of the early 1990's the Board of Commisioners in 1995 hired
KCM Inc., a consulting firm with wide experience in the preparation of CFHMP's, to undertake
the Upper Yakima CFHMP Funding for the Upper Yakima CFHMP was provided under an
agreement between Ecology and Yakima County, with Ecology contributing 75 percent of the
project costs through the state's Flood Control Assistance Account Program (FCAAP), and
Yakima County contributing the remainder from County funds, This plan was completed in
1998, adopted by the Board of Yakima County Commissioners on September 1, 1998, and
approved by the Washington State Department of Ecology (Ecology) on March 3, 2003. The
County adoption made it eligible for State and FEMA funding.
The CFHMP identified flooding issues along the plan reach in order to gain an understanding
of flood hazard management alternatives and develop a flood hazard management program to
address these issues. As part of the development of a citizen and agency participation process
an Advisory Committee of 22 members was formed and 8 meetings held during plan
development. The committee had members from local agencies, including the Cities and
citizens. A list of members is contained in Chapter 1. The following Long-term and short-term
goals and objectives were developed by the committee.
CFHMP GOALS AND OBJECTIVES
Long-term goals, which were established by the Advisory Committee for the 1998 Upper
Yakima River CFHMP, and are maintained in the update, include the following:
• Prevent the loss of life, creation of public health or safety problems, and damage
to public and private property
• Maintain the varied uses of existing drainage pathways and floodplains within
the County
• Establish and adopt a systematic and comprehensive approach to flood hazard
management
• Minimize the expenditure of public funds through effective flood hazard
management
• Prevent the degradation of surface and groundwater
• Establish a stable, adequate, and publicly acceptable long-term source of
financing for a flood hazard management program.
Objectives established to reach CFHMP goals include the following:
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Upper Yakima River Comprehensive Flood Hazard Management Plan
• Implement flood hazard management measures as approved in the CFHMP
• Give preference to nonstructural measures such as regulations and preservation
of existing drainage corridors
• Preserve floodplain uses that are compatible with periodic flooding. Discourage
land uses in the floodplain that are incompatible with periodic flooding
• Adopt flood control measures that preserve or enhance existing fishery, wildlife,
and other natural uses of the riparian zone
• Ensure that changes in land use witlun drainage corridors maintain or restore the
natural character wherever possible
• Integrate water quality needs with flood control needs and minimize the impact
of contaminants and sediment in stormwater entering receiving waters
• Pursue strategies for flood hazard management that balance engineering,
economic, environmental, and social factors
Maintain consistency with Yakima County and local comprehensive plans, the
state Growth Management Act, and related policy plans
Coordinate flood hazard planning with all interested and affected parties
Improve public understanding of flood hazard management through public
education
Establish a funding mechanism to implement the CFHMP
Develop structural and nonstructural measures to prevent or mi imize existing
flood problems
• Adopt regulations to prevent new development from causing or being
susceptible to flood damage.
A complete listing of the 1998 recommended actions, the implementing lead agency, and the
current status of those recommendations, is provided in Table 7-2 of the 2007 update The
majority of the non-structural actions have been completed or superceded. Details of these
recommended actions are contained in Chapter 8 of the 1998 CFHMP
One of the major recommendations of the 1998 CFHMP was the establishment of a Flood
Control Zone District (FCZD) to oversee implementation of the Upper Yakima CFHMP, and
preparation of other CFHMPs throughout the County. On January 13, 1998, the Board of
Yakima County Commissioners established the Yakima Countywide flood Control Zone
District as an independent taxing districts authorized by RCW 86.15, with the Board of County
Commissioners acting as the Supervisors of the District, and the Yakima County Engineer as the
head of the FCZD
The Yakima Countywide FCZD was not staffed until 2001, and revenue collected by the FCZD
that began in 1999, was used to establish an emergency fund for flood fighting in the County, as
the 1996 flood fight had severe impacts on the County's general fund
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EXECUTIVE SUMMARY
2007 UPPER YAKIMA CFHMP UPDATE
Between the adoption of the CFHMP in 1998, and 2002, a number of significant changes
occurred which impacted the 1998 CFHMP recommendations. The most significant of these
changes are summarized in Table ES -1.
TABLE ES -1
SUMMARY OF MAJOR CHANGES TO AND IMPACT ON THE 1998 CFHMP
Action
Nature of Change
Impact on CFHMP
Formation of the Yakima
Countywide Flood Control Zone
District
FCZD takes responsibility for
implementing CFHMP actions, providing
oversite, management and monitoring of
flood hazards in Yakima County Actions
on CFHMP recommendations establish
partnerships.
Implements many of the CFHMP
recommendations for the County as a
whole, and for some actions in this project
area. Many of the implemented actions
are for non-structural measures.
Completion of the FEMA
floodplain Maps in 1998
Regulatory environment altered.
Floodplain extent and elevations generally
reduced, although hydrology not updated
for floods of 1990s.
CFHMP formulated when maps were in
early draft stage, so that much discussion
regarding draft maps in the CFHMP is no
longer relevant.
Completion of Plan 2015, the
Yakima County Comprehensive
Plan
Regulatory environment altered.
Especially land use designations in
floodplain areas,
Many, but not all, of the concerns
regarding high density zoning in
floodplain were resolved in Plan 2015 and
are no longer relevant.
'Listing of Middle Columbia River
Steelhead and Bull Trout as
Threatened under the
Endangered Species Act
Regulatory and funding environment
altered. Actions that alter habitat for these
species, or that receive federal funding or
permits, must be designed to not effect or
degrade habitat conditions.
CFHMP did not specifically address the
biological attributes of the reach, or the
effect of the plan or individual actions on
habitat conditions in the reach.
Purchase of Floodplain Properties
by the US Bureau of Reclamation
Land use environment altered.
These properties will remain in
conservation status.
Change in potential future values of
properties in floodplain for ag or other
development. Eliminates the need for
some structural actions, alters the
configuration of others.
The completion of the Reaches
Report on stream processes in the
study reach
Improved understanding of riverine
processes, river mechanics and sediment
transport and deposition between the
levees.
Greater understanding of why federal
levees were near failure in 1996, why other
levees have repeatedly failed, past levee
raising and potential actions to reduce
danger of failure.
Proposed reconstruction of SR 24
Bridge
Change in physical environrnent and
increased flexibility in levee
reconfiguration.
Rendered the highest ranked structural
action in the plan not -implementable, and
provided opportunities for other actions.
Much of the need to update chapter 8 of the plan became apparent during the planning and
permitting process that WSDOT undertook for the new SR 24 bridge and related facilities. This
chapter deals with the analysis of flood problems, and corresponding flood hazard
management alternatives and programs. In that process, several committees were formed to
look at different aspects of the environment and the bridge design such as recreation, wetlands,
effect on ESA -listed species Participants in this process included Yakima County, the City of
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Upper Yakima River Comprehensive Flood Hazard Management Plan
Yakima, the Greenway Foundation, Diking Improvement District #1, WSDOT, Ecology,
WDFW, the Yakama Nation, and federal agencies such as NMFS, USFWS, USBOR, the Corps of
Engineers, and Federal Highways. Rivenne processes and their relationship to flood hazards
witlun the leveed area of the "gap to gap" reach of the Yakima River became a focal part of the
SR 24 committee discussions and permitting process.
Given the extent of the above impacts, and the the fact that the murucipalities affected by the
CFHMP, namely the Cities of Selah, Union Gap, and Yakima, had not adopted the 1998 plan, it
was decided in 2002 to revise and amend Chapter 8 of the CFHMP Once revised, the FCZD
would seek approval of the revised plan from the County and the above cities in the planning
area.
In 2004 the FCZD submitted Chapter 8 to the Yakima County Planning Department for analysis
on the consistency of the proposed amendments with the State Environmental Policy Act
(SEPA) decision for the original plan. County Planning determined that the amended Chapter 8
was substantively different from the original chapter 8 and required a full SEPA process.
Through the SEPA process, and after conversation with interested parties such as the City of
Yakima, WSDOT, Ecology, and others, plan adoption was conditioned on the complete update
of all portions of the plan prior to submission to the Board of Yakima County Commissioners
for approval, or to any of the cities. Revisions were requested to update information that has
become obsolete (refereces to prior versions of regulations, listings of needed actions that have
since been implemented, etc.) and to ensure consistency of all chapters with the revised content
of chapter 8 Also in the SEPA decision, and contained in this executive summary, is a general
plan for how the actions in the plan will be implmentented by the Flood Control Zone Distract
in cooperation with the partners listed above, and others such as the Yakama Nation,
Washington Department of Fish and Wildlife, and the United States Bureau of Reclamation.
Updating the 1998 plan was a process of updating Chapters 1 through 9 in accordance with the
ammended Chapter 8. The recommended actions in Chapter 8 were a process of: (a) subtraction
of actions no longer deemed appropriate given new information or already completed; (b),
addition of new actions that are needed, and (c) modification of several actions to be consistent
with new information. The List of these changes is given in Appendix B Actions are presented
in Chapter 8 in an order based on the severity of the flooding problems (pnoritized by the 1998
advisory committee) that those actions address. The most severely modified actions were those
physically associated with the SR 24 bridge and the properties acquired by USBR.
Modified recommendations in the CFHMP 2004 Amendment were directly related to the
enhanced understanding of the dominant processes driving flood hazards that came to light as
part of the SR 24 Bridge permitting process, although much of the new science was developed
by the BOR and CWU Recommendations include policy changes and additional studies
related to the processes driving flood hazards These recommended studies are either of a
general nature (i.e study the available sediment supply m this reach) or specific, such as the
recommendation for further study of the effects of levee relocation on adjacent infrastructure.
For instance, such future studies and environmental analysis will include assessing potential
impacts of levee relocation on the City of Yakima WWII' outfall, mixing zone, and water
quality of the Yakima River. Levee relocation studies and environmental analyses will include
identification and evaluation of measures to mitigate/identified adverse impacts
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. EXECUTIVE SUMMARY
RECOMMENDED ACTIONS
In this plan area the ability of flood protection facilities to withstand erosion and overtopping
by floodwaters was a primary consideration within the recommendations.
The 2007 CFHMP recommended actions detailed in Chapter 8, and Chapter 9, are summarized
below in Table ES -2. Recommended flood hazard management actions include construction
projects, studies to evaluate and fund new construction projects, new policy decisions, land use
modifications, enhancements to regulations, and options for retrofitting existing structures. In
Table ES -2. they have been grouped accordingly with the highest priority flood issues listed
first in each category
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Table ES -2
Summary of Recommended Actions
Structural, Non -Structural, Regulatory, Study
Issues
Addressed
Setback of the levees downstream ot SR 24 should not occur until the WWTP's ability to continue to discharge is assured.
LR5
Structural Actions
Reconfigured levees upstream of SR24 should tie into the new SR 24 bridge abutments. On the east side of the river, levee setback would
begin upstream of the Old Moxee bridge and continue to the SR 24 alignment.
LR5
Remove the western Old Moxee bridge abutment, located upstream of new SR24 alignment.
LR5
LR5
Levees Downstream of SR24, on the east side of the river will be set hack to allow the incorporation of the Newland Pits into the floodplain.
The levee should he located west of Blue Slough for a distance of approximately 2,300 feet south of SR 24, then crossing the slough and
continuing downstream.
Levees Downstream of SR24 on the west side of the river, currently protecting Yakima WWTP should be repaired to ensure protection of the
WW t'P itself and maintain the ability of the City ot Yakima WWTP to continue to discharge in conformance with state law
LR5
UR5, MR2,
The opportunity exists at the Beech Street Pit location (or widening ot the channel and improving (for sediment transport) the configuration
ot the levee system by setting back the levee opposite lrom the pit and this action should be taken. Spur dikes and additional bank
protection are recommended along the Beech Street levee to reduce levee erosion. Spur dikes recently installed at the East Selah Gravel Pit
should be monitored Burin; flood events to ensure that they are protecting 1-82 and the East Selah Pit levee.
To reduce the potential tor avulsion or levee failure at the Buchanan Lake/Beech Street Pit over the long term (i.e., in approximately 15-20
years or sooner if possible), the existing Terrace Heights bridge should be modified to improve sediment transport and reduce the
concentration of energy downstream, especially against the levee that protects the Beech Street Pit.
UR5, IvMR2,
UR5, MR2,
Existing Gravel Mining Sites: Due to the location of the East Selah Gravel Pit, large flood events will continue to affect the property in this
area. Following gravel extraction, long -terns modifications should include a levee designed to overtop during large flows.
The Flood Control Zone District should work with BIA, BOR, and other interested parties in replacing or modifying Wapato Dam to pass
bedload and fine sediment.
LR3
The levees at Union Farms also act as a choke point in this section of the river forcing the river against 1-82, and taking a fairly large amount
of floodplain surface out of the active floodplain. Removal of these levees would relieve the pressure against 1-82 and lower flood
elevations by allowing the river to expand across a larger floodplain.
LR3
The WSDOT should construct barbs similar to the existing downstream barbs to protect 1-82. The Spring Creek gate should he reinforced to
prevent failure during a future flood event or avulsion caused by pit capture. A new channel for Spring Creek (approximately 550 feet in
length) should be constructed outside of the 1-82 clear zone, with fish habitat elements installed in this new channel.
LR7
Retirement of the Fruitvale Diversion and Consolidation with the Current Nelson Dann Diversion
NA1
1m.lementation of Bank Protection on US T-Iighway 12 at the 164, Avenue Exit.
NA1
Based on the county -wide road closure database, prioritize roads requiring flood damage mitigation.
RW 12
RW3, LR1, UR1
The County should implement bank protection projects following established guidelines (e.g., King County 1993 or ISPG, 2003), modified for
Yakima County
The following are recommended to address operations and maintenance issues:
Consolidate maintenance requirements into one document following the steps outlined above
Ado.t a olic re.uirin, all new flood -control projects to define maintenance responsibilities and a funding source for operations,
RW16
•
ES -8
•
•
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EXECLITIVE SUMMARY
Table ES -2
Summary of Recommended Actions
maintenance, and repairs before acceptance by the County
Continually update and maintain a flood control facility inventory database to document the current condition of each flood control facility.
Rebuild the existing Greenway pathway levee to pre -flood conditions; however, install additional embankment protection by applying
heaves+ rrap in the highly erosive areas.
MR6
Study
Issues
Addressed
In addition, an inventory of the existing structural adequacy and capacity of all levees that protect existing floodplain mines and pits should
be undertaken.
UR5, MR2,
Develop a high water elevation database to evaluate changes in river channels
LR3
Obtain additional high water elevations throughout the floodplain resulting from the February 9, 1996, flood
RW1
RW1
RW1
Obtain accurate topographic data throughout the floodplain specifically for the left bank levee and floodplain downstream of the SR 24
bridge, 1-82, and the floodplain near East Selah
Once this data is obtained, a new hydrologic and hydraulic analysis should be performed to FEMA standards, this will allow the design of
the facilities specified above in issue LR5, and shorten the time needed to amend the FEMA maps after implementation of those actions.
Request that FEMA produce a digital floodplain map that combines all jurisdictions and reflects recent data for use in the County's GIS.
RW1
Given the long-term nature of this type of flood hazard (channel migration, sediment accumulation, erosion), a study to determine these
values and to monitor sediment transport and energy should be implemented.
RW20
Rth72, MR8
The County, WDFW, and the Yakama Indian Nation should identity and specifically list fish habitat enhancement areas
Assemble GIS coverages documenting closed and damaged roads from historic flood events discussed in the CFIiMP
RW15
RW15
Obtain flood damage GIS coverages for recent and historical floods as they become available from FEMA
The County should hire a public education officer to manage a public education and CRS program
RW18,
RW7
Non -Structural Actions
( Flood Fight)
Issues
Addressed
During flood events posing risk, formalize procedures for dispatching field teams and volunteers to critical locations along rivers and creeks
to manually collect real-time river information
Finish compiling time delays from the BOR in flood peaks between locations along the Yakima River for various flood magnitudes
Continue reviewing and compiling information on past flood events to create a database that correlates road closures with river stage and
discharge
Develop and communicate to the public a policy on sandbag distribution during flood events (use periodic public outreach methods to
reiterate this policy).
Develop a flood inundation map for distribution to the public
1 -time, automatic gauging stations within the upper watershed of tributary creeks'
Create a Community Alert Network for use at the EOC
W19
Non -Structural
Issues
ES -9
Upper Yakima River Comprehensive Flood Hazard Management Plan
Table ES -2
Summary of Recommended Actions
Addressed
(Funding)
Review tie ade_qracy of dedicated funds versus projected costs.
RW13
RW13
RW13
RW13
Actively pursue slate and federal grant programs to supplement funding provided by flood control district (see Tables 9-1 and 9-3, in
Chapter 9).
Adopt a funding policy similar to polices developed in Plan 2015
Investigate the value and need for sub -zones within the FCZD
Provide direction and support to secure funding for large scale actions which involve cooperation across jurisdictions and agencies
RW13
Comity should provide guidance in designing private bank protection projects.
RW3, LR1, UR1
Limit development in rapid channel migration areas by promoting the Open Space Taxation Program in a public awareness campaign (see
issue RW10—Acquisition/Preservation of Floodplain Open Spacc)
RW3, LR I, UR1
RW3, L121, UR1
Adopt and enforce design standards, such as onsite detention, to limit or mitigate increased erosion potential resulting from new
development.
The County should submit a letter of intent for participation in the COE 1135 program to obtain funding for fish habitat restoration
consistent with flood protection within the plan river reaches.
RW2,
MR8
RW17
RVV1.0
The County should pursue funding through the Reigle Community Development and Regulatory Improvement Act, Robert T Stafford
Disaster Relief and Emergency Assistance Act, Flood Control Assistance Account Program (FCAAP), Pre -Disaster Mitigation (PDM)
progam, and Hazard Mitigation Grants Program (11MGP).
The County should continue to operate and promote the Open Space Taxation Program.
Pursue funding through state and federal programs to purchase high -hazard floodplain properties or development rights for open space
use.
RW10
The County should enroll in the -CRS using a "short form" (Appendix E of the CRS Coordinator's Manual)
RW18,
RW7
The County should submit the full set of required documentation to update its CRS rating following adoption of the CFHMP
RW18,
RW7
Establish a maintenance budget for Greenway facilities.
MR6
Non -Structural
(Regulatory)
Issues
Addressed
UR5, MR2,
LR3
LR3
Future Gravel Mn nig Sites: Development of future gravel extraction sites in the floodplain of the Yakima River and Naches River will be
driven lay the Yakima County Comprehensive Plan
Adopt and follow the proposed Plan 2015 County policy tor management of the riverine environments.
Add compensatory storage requirements to the County's CAO.
Revise base floodproofing and elevation building standards based on February 9, 1996, high water data.
RVV1
Require disclosure of floodplain status in the subdivision ordinance for all newly created parcels.
RW6
Sections 5.28.020(1)(a), 5.28.020(2), and 5.28.020(3) of the County's CAO should be revised to require all new construction and substantial
improvement, regardless of intended land use, to he elevated or floodproofed.
RW4,
RW5
RW4,
RW5
CAO Sections 5.32.010(2) and 5.36.010(2) pertaining to requirements for siting utility lines in the floodway fringe and floodway should be
consolidated within Section 4.14 pertaining to siting of utilities in I-1RCAs.
•
ES -10
•
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EXECUTIVE SLIMfvIARY
Table ES -2
Summary of Recommended Actions
CAO Section 5.36 010(1) should be deleted.
RW4,
RW5
A new CAO Section 5.28.010(d) should be added as follows:
Construction of new critical facilities shall be, to the extent possible, located outside the limits of the base flood plain
RW4,
RW5
RW4,
RW5
The County should determine if each jurisdiction's shoreline ordinance requires mitigation similar to zero -rise methods for the area within
100 feet of the OHWM or floodway If so, language from the shoreline ordinances should be repeated in each jurisdiction's flood hazard
ordinance It not, Yakima County CAO Section 5.28.010(a)(3) should be replicated in each jurisdiction's ordinance
City jurisdictions should integrate flood hazard items included in the County's CAO
RW4,
RW5
A fly design standard of the Greenway Master Plan during Class 2 review of developments within floodplain or Greenway overlay zones.
RW10
Extend Greenway overlay zoning beyond the Yakima Urban Area within conservation, recreation, and natural areas designated in the
Master Plan.
RW10
Obtain from FEMA the best available digital flood hazard map that meets the objectives listed below-
Accuracy Establish definitive and accurate representations of the floodway, 100 -year floodplain, Special Flood Hazard Areas (SFHAs), and
Base Flood Elevations (BFEs)
Completeness: Ensure that all of the items listed above are present in the GIS database and that the database includes all jurisdictions within
Yakima County
Accessibility. Enhance the County's ability to perform floodplain determinations, measure areas of SFHAs, determine BFEs of specific
locations, and realize time savings in the permit process
Community Review' Ensure that sufficient local review of flood hazard information has occurred prior to release of that data for public use.
RW15
OSA1
Issues
Addressed
The Countyshould adopt a Corn .rehensive Stormwater Mana•ement Plan to reduce localized floodin. in the Yakima urban areas
Non -Structural
Re,ulator , Education)
Construct a GIS permit review tool.
RW15
Continue Standard GIS data u dates.
RW15
Structural, Non -Structural
(Funding, Flood Fight, Education)
Issues
Addressed
MR7, UR3,
UR4
The following are recommended to minimize damage to Greenway and Elks Golf Course facilities:
Floodproof repetitively damaged structures by moving them to a higher elevation or installing flood walls or sealant
Rebuild Greenway pathways to higher design standards such as using more erosion -resistant embankment protection
Establish a maintenance budget to provide funding for the repair of inevitable future flood damage to roadways, pathways, and the Elks
Golf Course
Establish flood response teams to remove temporary structures prior to a impending flood event
Educate Greenway users about flooding by installing interpretive signs near damaged sites that describe floodplains, floodways, effective
floodplain management, and how various actions can aggravate flooding and flood damage
Continually monitor cumulative effects of development in the area to limit the potential of aggravating flood damage.
ES -11
Lipper Yakima River Coiuprelienstve Flood Hazard Management Plan
Table ES -2
Summary of Recommended Actions
Issues
Addressed
Structural, Non -Structural, Study
To address flood damage within southeastern Union Gap, the following are recommended.
-ate floodproofing techniques into the City ot Union Gap's pump station
Promote floodproofing and flood insurance to Union Gap residents who experienced damaged during the February 1996 flood
Construct the Wide Hollow Creek high-flow bypass as recommended in the 1993 draft City ot Yakima Comprehensive Stormwater
tvtanagement Plan for the urban area,
Conduct a comprehensive drainage study for the Ahtanum Creek watershed as recommended in issue OSA1—Continued Flood Damage
Outside the CFFIMP Study Area.
LR6
Study, Non-structural
(Regulatory)
Issues
Addressed
Submit certification forms and supporting data to FEMA to obtain a Map Revision in Union Gap following FEMA guidelines (FEMA 1990)
RW1
ES -12
• •
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PROJECT IMPLEMENTATION STRATEGY
Several of the recommended structural actions and the studies needed to support them are large
actions and will require funding at a scale that cannot be entirely be funded by any single
funding source. The FCZD can provide, or contract, the expertise required to design and
implement these projects and studies, as well as seek funds. Detailed analysis is required for
each of the structural actions in order to maximize beneficial and minimize potential
detrimental impacts. The array of levee relocation and stabilization projects require study as an
overall set of coordinated actions so that the benefits and impacts can be understood and
realized in a holistic manner The following considerations are to be included: flood hazard,
critical infrastructure such as water treatment, diversion, and distribution systems; the state,
local, and federal transportation systems, and natural resources of very high importance to the
economy of the Yakima Valley such as water quality, recreation, and fish and wildlife habitat.
Timelines for several of these activities, particularly large ones, are dependent on external
agencies. Cooperation across jurisdictions and agency responsibilites will be necessary to
successfully design, fund, implement, and maximize benefits from these large scale actions and
studies, and to ensure that multiple objectives can be met.
Funding opportunities will be increased through the existence and adoption of this plan, plus
coordination amongst affected parties and presence of a lead proponent for each project. For the
largest actions, there will likely be the need to approach athorities such as the Legislature and
Congress to provide or allow funds to be spent on these multi -objective and cross jurisdictional
projects.
For large flood projects, the Yakima County Flood Control Zone District has the authority and
can perform the role of lead or coordinator across the vanety of authorities to attain multi-
agency/multijursdictional cooperation, participtation, and joint decision-makmg.
Environmental review and permitting will be required for structural projects. Mitigation for
impacts identified during additional studies and environmental review will be developed in
cooperation with affected agencies or jurisdictions. Projects shall not proceed to construction
unless impacts are mitigated in accordance with state and federal laws, local policies and codes,
and this CFHMP
ES -13
•
•
DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT
Planning Division
129 North Second Street, 2nd Floor Yakima, Washington 98901
(509) 575-6183 • Fax (509) 575-6105 • www.ci.yakima.wa.us
CITY OF YAKINIA
NOTICE OF APPLICATION AND ENVIRONMENTAL REVIEW
DATE: April 14, 2008
TO: SEPA Reviewing Agencies, Applicant and Adjoining Property Owners
FROM: Bruce Benson, Acting Planning Manager
SUBJECT: Notice of Application & Environmental Review of the adoption by the
City of Yakima of the Upper Yakima River Comprehensive Flood Hazard
Management Plan RM 107-128 June 2007 Update, Including New
Appendix F ("CFHMP" herein)
ENVIRONMENTAL REVIEW
The City of Yakima has reviewed this proposal for probable adverse environmental
impacts and expects to issue a determination of nonsignificance (DNS) for this proposal
A copy of the subsequent threshold determination may be obtained on request and may
be appealed pursuant to YMC 6 88 170 The optional DNS process in WAC 197-11-355
is being used This may be your only opportunity to comment on the environmental
impacts of the proposal.
Comment due date: May 5, 2008
Agencies, tribes, and the public are encouraged to review and comment on the proposal
and its probable environmental impacts All written comments received by May 5, 2008
will be considered prior to issuing the final SEPA determination on this application
The following conditions have been identified that may be used to mitigate the adverse
environmental impacts of the proposal No impacts identified
Required Permits: N/A
Required Studies: None
Existing Environmental Documents:
1 SEPA Final Mitigated Determination of Non -Significance issued by Yakima
County Planning Services Division dated July 22, 2005, together with files and
records associated therewith,
Yakima
a-rreeour,
11111?
1994
2 USGS Sediment Transport Study and Geomorphic Analysis, and
3 Bureau of Reclamation Modeling. Study, and Yakima River Study.
Preliminary determination of the development regulations that will be used for
project mitigation and consistency: City of Yakima Urban Area Comprehensive Plan,
Yakima Municipal Code, Washington Administrative Code
PROPOSAL DESCRIPTION
The City of Yakima Department of Community & Economic Development has received
an application from the City of Yakima Wastewater division for the environmental
re\,iew of the CFHMP, which is proposed for adoption by the City of Yakima The
CFHMP describes the studies, findings, and recommendations of the Yakima
Countywide Flood Control Zone District (FCZD) for flood hazard prevention and
floodplain restoration along the Yakima River between Selah Gap and Union Gap.
Adoption of the CFHMP is considered a non -project action under WAC 197-1 1-
704(2)(b) and does not implement any specific project, such as construction or
management activity located in a defined geographical area under WAC 197-1 1-
704(2)(a)
The CFHMP describes a coordinated approach to flood hazard management within a
complex interagency and inter -jurisdictional context Implementation of projects and
policy proposals that are consistent with the CFHMP will require further assessment for
environmental significance, regulatory consistency, and policy preferences of the relevant
jurisdictions and agencies
NOTICE OF APPLICATION
Proposal Study Area: Upper Yakima River from the northern boundary of Yakima
County to Union Gap and along the Naches Ri\er from the Twin
Bridges on SR 12 to its confluence with the Yakima River
Proposal Applicant: City of Yakima Wastewater Di\ inion
File Number: UAZO EC #23-08
Date of application: April 5, 2008
Date of determination of completeness: April 9, 2008
PUBLIC REVIEW & COMMENT
Your views on this proposal are welcome All written comments received by Ma) 5,
2008 \\ ill be considered prior to issuing the final decision on this application Please mail
your comments on the environmental review of this proposal to
Bruce, Benson Acting Planning Manager
•
•
•
•
•
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City of Yakima, Department of Community & Economic Development
129 North 2nd Street
Yakima, WA 98901
Please be sure to reference the file number in your correspondence (UAZO EC #15-0S)
NOTICE OF DECISION
A copy of the SEPA threshold determination will be mailed to you after the end of the
20 -day comment period
The file containing the complete application is available for public review at the City of
Yakima Planning Division, 2nd floor City Hall If you have any questions on this
proposal, please call Jeff Peters, Assistant Planner at (509) 575-6163 or e-mail at
Jpeters@cl yakima.wa us
Encl Environmental Checklist & Appendix F
RECEIVED
APR 0 8 2008
CITY OF YAKIMA
Adoption of Upper Yakima River Comprehensive Flood Hazard ManagementlSriiINING DIV,
RM 107-128 June 2007 Update, Including New Appendix F
City Of Yakima
SEPA Environmental Checklist
A BACKGROUND
1 Name of proposed project, if applicable: Nonproject action: adoption by the City
of Yakima of the Upper Yakima River Comprehensive Flood Hazard Management
Plan RM 107-128 June 2007 Update, Including New Appendix F ("CFNMP" herein)
Name of applicant: City of Yakima
3. Address and phone number of applicant and contact person:
City of Yakima
129 North Second Street
Yakima, WA 98901
Max Linden
(509) 575-6077
4 Date checklist prepared: Apnl 7, 2008
5 Agency requesting checklist: City of Yakima
6 Proposed timing or schedule (including phasing, if applicable): Adoption of
CFHMP during May, 2008.
7 Do you have any plans for future additions, expansion, or further activity related
to or connected with this proposal? If yes, explain.
No. Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area WAC
197-1 1-704(2)(a).
The CFHMP descnbes a coordinated approach to flood hazard management within a
complex interagency and inter-junsdictional context.
Implementation of projects and policy proposals consistent with the CFHMP will
require future assessment for environmental significance, regulatory consistency, and
policy preferences of relevant jurisdictions and agencies.
1-1. Prol lakiina,Mandatory WVv
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8. List any environmental information you know about that has been prepaya.Aitlilh
will be prepared, directly related to this proposal.
SEPA Final Mitigated Determination of Non -significance issued by Yakima County
Planning Services Division dated July 22, 2005, together with files and records
associated therewith. In addition. several studies (e.g., USGS Sediment Transport
Study and Geomorphic Analysis, Bureau of Reclamation Modeling Study, and the
Yakima River Study) ha\ e been prepared and are ongoing dealing with floodplain
restoration on the Yakima River
The CFHMP describes a coordinated approach to flood hazard management within a
complex interagency and inter -jurisdictional context
Implementation of projects and policy proposals consistent with the CFHMP will
require future assessment for environmental significance, regulatory consistency, and
policy preferences of relevant junsdictions and agencies
9 Do you know' whether applications are pending for governmental approvals of
other proposals directly affecting the property covered by your proposal? If yes,
explain.
Central Premix (CPM) has current permits and applications submitted for mining and
related activities on CPM -owned land on both sides of Riverside Road, which is
within the CFHMP study area.
10 List any government approvals or permits that will be needed for your proposal,
if known.
11
Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b) Adoption
of the CFHMP does not implement any specific project, such as construction or
management activity located in a defined geographical area WAC 197-1 1-704(2)(a)
Give a brief, complete description of your proposal, including the proposed uses
and the size of the project and site. There are several questions later in this
checklist that ask you to describe certain aspects of your proposal. You do not
need to repeat those answers on this page. (Lead agencies may modify this form
to include additional specific information on project description.)
The CFHMP describes the studies, findings, and recommendations of the Yakima
Countywide Flood Control Zone District (FCZD) for flood hazard prevention and
floodplain restoration along the Yakima River between Selah Gap and Union Gap
12 Location of the proposal. Give sufficient information for a person to understand
the precise location of your proposed project, including a street address, if any,
and section, township, and range, if known. If a proposal would occur over a
H Proj 1 akunav\landator \V\4
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gifCEO/EC,
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CITY OF YAKIMA
range of area, provide the range or boundaries of the site(s). Provide a faN1NG DIS/
description, site plan, vicinity map, and topographic map, if reasonably
available. While you should submit any plans required by the agency, you are
not required to duplicate maps or detailed plans submitted with any permit
applications related to this checklist.
The CFHMP is for the Upper Yakima River from the northern boundary of Yakima
County to Union Gap and along the Naches River from the Twin Bndges on SR 12 to
its confluence with the Yakima River.
B ENVIRONMENTAL ELEMENTS
1. Earth
a General description of the site (circle one): Flat, rolling, hilly, steep slopes,
mountainous, other...
The CFHMP study area covers a combination of flat, rolling, hilly, and steep
slopes along the lower Naches River and Yakima River in northern Yakima
County.
b. What is the steepest slope on the site (approximate percent slope)?
40-50%
c. What general types of soils are found on the site (for example, clay, sand,
gravel, peat, muck)? If you know the classification of agricultural soils,
specify them and note any prime farmland.
The lower elevations, along the Naches and Yakima Rivers, are pnmanly
Weirman-Naches-Ashere series which are well drained, level to gently sloping,
consisting of flood deposits To the west, soils change to the Ritzville-Warden-
Starbuck series and then to the Harwood-Gorst-Cowiche series. These series
range in depth from very shallow to quite deep, well -drained, level to very
steep To the south of Yakima and west of Union Gap, along Wide Hollow
Creek, is the Umapme-Esquatzel senes which are deep, well -drained to poorly -
drained, level to moderately steep They are found on terraces and floodplains
d Are there surface indications or history of unstable soils in the immediate
vicinity? If so, describe.
According to the Yakima Urban Area Comprehensive Plan, locations exist
within the CFHMP study area that are oversteepened and therefore high nsk.
e Describe the purpose, type, and approximate quantities of any filling or
grading proposed. Indicate source of fill.
H. Pror'lakitna.:Mlandatony WW
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PLANN'?i C.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-11-704(2)(a)
f Could erosion occur as a result of clearing, construction, or use? If so,
generally describe.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-11-704(2)(a)
About what percent of the site will be covered with impervious surfaces
after project construction (for example, asphalt or buildings)?
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-11-704(2)(a)
h Proposed measures to reduce or control erosion, or other impacts to the
earth, if any:
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
2 Air
a. What types of emissions to the air would result from the proposal (i.e., dust,
automobile, odors, industrial wood smoke) during construction and when
the project is completed? If ani, generally describe and give approximate
quantities, if known.
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-11-704(2)(a)
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b. Are there any off-site sources of emissions or odor that niay affect yainlrytyiT;G D V
proposal? If so, generally describe.
No
c Proposed measures to reduce or control emissions or other impacts to air, if
any:
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
3 Water
a. Surface:
1) Is there any surface water body on or in the immediate vicinity of the
site (including year-round and seasonal streams, saltwater, lakes,
ponds, wetlands)? If yes, describe type and provide names. If
appropriate, state what stream or river it flows into.
Yes. The Yakima River, Naches River, Cowiche Creek, Wide Hollow
Creek, Ahtanum Creek, Blue Slough, and Moxee Drain.
2) Will the project require any work over, in, or adjacent to (within 200
feet) the described waters? if yes, please describe and attach available
plans.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
3) Estimate the amount of fill and dredge material that would be placed
in or removed from surface water or wetlands and indicate the area of
the site that would be affected. Indicate the source of fill material.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a)
4) Will the proposal require surface water withdrawals or diversions?
Give general description, purpose, and approximate quantities, if
known.
H Proitl akima ,Mandatory SYN
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PLANNING
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b) Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
5) Does the proposal lie within a 100 -year floodplain? If so, note location
on the site plan.
Yes The CFHMP study area addresses the Yakima River and most of its
shoreline is within the 100 -year floodplain.
6) Does the proposal involve any discharges of waste materials to surface
waters? If so, describe the type of waste and anticipated volume of
discharge.
NA Adoption of the CFHMP is a nonproject action WAC 197-1 1-
704(2)(b) Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
b
Ground -
1) Will ground water be withdrawn, or will water be discharged to
ground water? Give general description, purpose, and approximate
quantities, if known.
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b) Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a)
2) Describe waste material that will be discharged into the ground from
septic tanks or other sources, if any (for example: domestic sewage;
industrial, containing the following chemicals ...; agricultural; etc.).
Describe the general size of the system, the number of such systems,
the number of houses to be served (if applicable), or the number of
animals or humans the system(s) are expected to serve.
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a)
c Water runoff (including stoiniwater)•
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1) Describe the source of runoff (including storm water) and mecY
tp2gp
collection and disposal, if any (include quantities, if known). Where
will this water flow? Will this water flow into other waters? If so,
describe.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
2) Could waste materials enter ground or surface waters? If so,
generally describe.
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-1 1-704(2)(a)
d. Proposed measures to reduce or control surface, ground, and runoff water
impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
4. Plants
a. Check or circle types of vegetation found on the site:
Within the CFHMP study area
X Deciduous tree alder, maple, aspen; other
X Evergreen tree fir, cedar, pine, other
X Shrubs
X Grass
X Pasture
X Crop or grain
X Wet soil plants: cattail, buttercup, bulrush, skunk cabbage, other
X Water plants• water lily, eelgrass, milfoil, other
X Other types of vegetation (npanan plants where the outfall enters the
n er)
b. What kind and amount of vegetation will be removed or altered?
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NA Adoption of the CFHMP is a nonproject action. WAC 197-11-704 (Ai )Or VA
Adoption of the CFHMP does not implement any specific project, such as Li(
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
c. List threatened or endangered species known to be on or near the site.
Within the CFHMP study area
Plant Listing
Scientific Name
Common Name
State Status
Federal
Status
Astraga/usco/umbianus
Columbia milk -vetch
Threatened
SC
Cvpripedum
Jascicit/atuni
Clustered lady's-
slipper
Threatened
SC
Erigeron Basalncus
Basalt daisy
Threatened
C
Lobelia Kalmsi
harm's lobelia
Endangered
E
Lomaticun Tuberosurn
Hoover's desert-
parsley
Threatened
SC
Sis.vrincllunli
SUrmentoSillli
Pale blue-eyed grass
Threatened
SC
Tauschla Hoover!
Hoover's tauschia
Threatened
SC
SC = Species of Concern
C = Candidate
E = Endangered
d Proposed landscaping, use of native plants, or other measures to preserve
or enhance \egetation on the site, if any:
NA Adoption of the CFHMP is a nonproject action WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-1 1-704(2)(a).
5 Animals
a. Circle any birds and animals which have been observed on or near the site or are
known to be on or near the site.
Within the CFHMP study area
Birds
quail
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hawk. heron. eagle. songbirds. other: ducks. pheasant.
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Mammals: deer. elk. beaver, other: skunks, coyote
Fish: bass. salmon. trout, hemng, shellfish, other:
b. List any threatened or endangered species known to be on or near the site.
Within the CFHMP study area:
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Bald Eagle
Ferruginous Hawk
Golden Eagle
Great Blue Heron
Prairie Falcon
Ring Necked Snake
Fish: Salmon
Steelhead
c. Is the site part of a migration route? If so, explain.
Possible migration within the CFHMP study area. Salmon and steelhead
migrate on the Yakima River. Waterfowl migrating on the Pacific Flyway use
the rivers, sloughs; and nearby agricultural lands.
d. Proposed measures to preserve or enhance wildlife, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
6. Energy and Natural Resources
a What kinds of energy (electric, natural gas, oil, wood stove, solar) will be
used to meet the completed project's energy needs? Describe whether it
will be used for heating, manufacturing, etc.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
b. Would your project affect the potential use of solar energy by adjacent
properties? If so, generally describe.
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CITY OF ADNA Adoption of the CFHMP is a nonproject action. WAC 197-11-704(�3N
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
c What kinds of energy conservation features are included in the plans of this
proposal? List other proposed measures to reduce or control energy
impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
7. Environmental Health
a Are there any environmental health hazards, including exposure to toxic
chemicals, risk of fire and explosion, spill, or hazardous waste, that could
occur as a result of this proposal? If so, describe.
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
1) Describe special emergency services that might be required.
NA. Adoption of the CFHMP is a nonproject action WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a)
2) Proposed measures to reduce or control environmental health
hazards, if any:
NA Adoption of the CFHMP is a nonproject action WAC 197-11-704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a)
b. Noise
1) What types of noise exist in the area w hich may affect y our project
(for example: traffic, equipment, operation, other)?
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NA Adoption of the CFHMP is a nonproject action. WAC 197 -111 -LA M1NG a!
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
2) What types and levels of noise would be created by or associated with
the project on a short-term or a long-term basis (for example: traffic,
construction, operation, other)? Indicate what hours noise would
come from the site.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
3) Proposed measures to reduce or control noise impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-
704(2)(b). Adoption of the CFHMP does not implement any specific
project, such as construction or management activity located in a defined
geographical area. WAC 197-11-704(2)(a).
8 Land and Shoreline Use
a What is the current use of the site and adjacent properties?
Within the CFHMP study area, the City of Yakima wastewater treatment plant
(WWTP) site is currently used for wastewater treatment. Pasture is located to
the north and east of the WWTP. The interstate forms the western boundary
The land to the south of the WWTP is owned by the City and leased out for hay
production Other areas within the CFHMP study area are used for many
different purposes, including. suburban, light industrial, and other uses
b. Has the site been used for agriculture? If so, describe.
Yes Some of the areas within the CFHMP study area have been used for
agriculture, pnmanly in the area east of the Yakima River. between SR -24 and
the Union Gap.
c Describe any structures on the site.
Within the CFHMP study area are dikes, bridges, roads. City of Yakima
wastewater treatment plant (WWTP) outfall, imgation drains. etc
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d. Will any structures be demolished? If so, what?
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NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
e. What is the current zoning classification of the site?
Within the CFHMP study area are lands zoned for many different uses,
including suburban, light industnal, and other uses
f. What is the current comprehensive plan designation of the site?
Within the CFHMP study area are lands designated by the Yakima Urban Area
Comprehensive Plan as low density residential, medium density residential.
arterial commercial and professional office.
g If applicable, w hat is the current shoreline master program designation of
the site?
The designation of the shoreline within the CFHMP study area and inside the
City of Yakima. is rural, urban, and conservancy.
h Has any part of the site been classified as an "environmentally sensitive"
area? If so, specify.
There are areas within the CFHMP study area designated as sensitive areas
within the Yakima Service Area. These include wetlands, groundwater
recharge areas, conservation areas, and geologically hazardous areas
1 Approximately how many people would reside or work in the completed
project?
1
NA. Adoption of the CFHMP is a nonproject action WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
Approximately how man} people would the completed project displace?
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
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k Proposed measure to avoid or reduce displacement impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
1. Proposed measures to ensure the proposal is compatible with existing and
projected land uses and plans, if any:
Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
A new Appendix F has been added to the CFHMP and is intended as a
statement reconciling any potential conflicts between the CFHMP and existing
land use plans within the City of Yakima.
9 Housing
a. Approximately how many units would be provided, if any? Indicate
whether high, middle, or low-income housing.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
b. Approximately how many units, if any, would be eliminated? Indicate
whether high, middle, or low-income housing.
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project; such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
c Proposed measures to reduce or control housing impacts, if any:
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NA Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
10. Aesthetics
a What is the tallest height of any proposed structure(s), not including
antennas; what is the principal exterior building material(s) proposed?
NA Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-1 1-704(2)(a)
b What views in the immediate vicinity would be altered or obstructed?
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
c Proposed measures to reduce or control aesthetic impacts, if any:
NA. Adoption of the CFHMP is a nonproject action WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management acti\ ity located in a defined geographical area
WAC 197-11-704(2)(a)
11 Light and Glare
a What type of light or glare will the proposal produce? What time of day
would it mainly occur?
NA. Adoption of the CFHIMIP is a nonproject action WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-11-704(2)(a)
b. Could light or glare from the finished project be a safety hazard or
interfere with views?
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NA Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
c What existing off site sources of light or glare may affect your proposal?
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
d. Proposed measures to reduce or control light and glare impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
12. Recreation
a. What designated and informal recreational opportunities are in the
immediate vicinity?
There is an arboretum, greenway path along the west side of the Yakima River,
and a private park; state park and City park. Throughout the CFI -IMP study
area, there are numerous parks and recreational opportunities along the Yakima
River and other surface waters.
b. Would the proposed project displace any existing recreational uses? If so,
describe.
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
c. Proposed measures to reduce or control impacts on recreation, including
recreation opportunities to be provided by the project or applicant, if any :
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
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construction or management activity located in a defined geographical arcgryOF A
WAC 197-11-704(2)(a). PLANNING DIV.
13 Histonc and Cultural Preservation
a. Are there any places or objects listed on, or proposed for, national state, or
local preservation registers known to be on or next to the site? If so,
generally describe.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
It is unknown what significant histoncal and cultural resources may exist within
the CFHMP study area.
b Generally describe any landmarks or evidence of historic, archaeological,
scientific, or cultural importance known to be on or next to the site.
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
It is unknown what significant histoncal and cultural resources may exist within
the CFHMP study area.
c Proposed measures to reduce or control impacts, if any:
NA Adoption of the CFHMP is a nonproject action WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
14 Transportation
a. Identify public streets and highways serving the site, and describe proposed
access to the existing street system. Show on site plans, if any.
Portions of SR 24, SRI 2, I-82, and Yakima Avenue are within the CFHMP
study area.
b Is the site currently served by public transit? If not, what is the
approximate distance to the nearest transit stop?
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Portions of the CFHMP study area are currently served by public transit A� r� IjlA
c. How many parking spaces would the completed project have? How many'
would the project eliminate?
NA Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
d. Will the proposal require any new roads or streets, or improvements to
existing roads or streets, not including driveways? If so, generally describe
(indicate whether public or private).
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area
WAC 197-1 l -704(2)(a).
e. Will the project use (or occur in the immediate vicinity of) water, rail, or
air transportation? If so, generally describe.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b).
Adoption of the CFHMP does not implement any specific project. such as
construction or management activity located in a defined geographical area
WAC 197-1 l -704(2)(a).
f. How many vehicular trips per day would be generated by the completed
project? If known, indicate when peak volumes would occur.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
g.
Proposed measures to reduce or control transportation impacts, if any:
NA. Adoption of the CFHMP is a nonproject action. WAC 197-11-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
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15. Public Services
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CITY OF YAK.
D.
a. Would the project result in an increased need for public services (for
example: fire protection, police protection, health care, schools, other)? If
so, generally describe.
NA Adoption of the CFHMP is a nonproject action WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
b. Proposed measures to reduce or control direct impacts on public services, if
any.
NA. Adoption of the CFHMP is a nonproject action. WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project. such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a)
16. Utilities
a Circle utilities currently available at the site:
Within the CFHMP study area. Electricity, natural gas. water. refuse service. telephone. sanitary
sewer. septic system, other
b Describe the utilities that are proposed for the project, the utility providing
the service, and the general construction activities on the site or in the
immediate vicinity which might be needed.
NA Adoption of the CFHMP is a nonproject action WAC 197-1 1-704(2)(b)
Adoption of the CFHMP does not implement any specific project, such as
construction or management activity located in a defined geographical area.
WAC 197-11-704(2)(a).
C SIGNATURE
The abo\ e answers are true and complete to the best of my knowledge I understand that
the lead agency is relying on them to make its decision
Signature
Title
r
City of Ya kkma Wastewater!anager
Date Submitted Apnl 8. 2008
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D. SUPPLEMENT SHEET FOR NONPROJECT ACTIONS (To be com p leted by th�'iY OF YAKI��.
LAi�NING DIV.
applicant )
(Do not use the following for project actions )
Because these questions are very general, it may be helpful to read them in conjunction with the
list of the elements of the environment. When answering these questions, be aware of the extent
the proposal, or the types of activities likely to result from the proposal, would affect the item at
a greater intensity or at a faster rate than if the proposal were not implemented
1. How would the proposal be likely to increase discharge to water; emissions to air;
production, storage, or release of toxic or hazardous substances; or production of noise?
Adoption of the CFI -IMP would not be likely to increase discharge to water; emissions to air;
production, storage, or release of toxic or hazardous substances; or production of noise.
Implementation of projects consistent with the CFHMP would likely have a beneficial effect
on discharge to water and an unknown effect on emissions to air; production, storage, or
release of toxic or hazardous substances; and production of noise.
Proposed measures to avoid or reduce such increases are: None
2. How would the proposal be likely to affect plants, animals, fish, or marine life?
Adoption of the CFHMP would not be likely to affect plants, animals, fish, or marine life.
Implementation of projects consistent with the CFHMP would likely have a beneficial effect
on fish life and an unknown effect on plants, animals, and marine life.
Proposed measures to protect or conserve plants, animals, fish, or marine life are:
None
3. How would the proposal be likely to deplete energy or natural resources?
Adoption of the CFHMP would not be likely to deplete energy or natural resources.
Implementation of projects consistent with the CFHMP would have an unknown effect on
energy and natural resources.
Proposed measures to protect or conserve energy and natural resources are: None
4. How would the proposal be likely to use or affect environmentally sensitive areas or
areas designated (or eligible or under study) for governmental protection; such as parks,
wilderness, wild and scenic rivers, threatened or endangered species habitat, historic or
cultural sites, wetlands; floodplains, or prime farmlands`'
Adoption of the CFHMP would not be likely to affect environmentally sensitive areas or
areas designated for governmental protection. Implementation of projects consistent with the
CFHMP would likely have a beneficial effect on habitat, wetlands, and floodplains; have an
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unknown effect on parks, wilderness, wild and scenic rivers, and historic and cultural sif ANNIN
•
and would likely reduce some farmlands adjacent to the Yakima River
Proposed measures to protect such resources or to avoid or reduce impacts are: None
5. How would the proposal be likely to affect land and shoreline use, including whether it
would allow or encourage land or shoreline uses incompatible with existing plans`'
Adoption of the CFHMP might have an effect on land and shoreline use pursuant to Ch.
86.12 RCW. Implementation of projects consistent with the CFHMP would likely have an
unknown effect on land and shoreline use
Proposed measures to avoid or reduce shoreline and land use impacts are: Adoption of
new Appendix F to the CFHMP
6. How would the proposal be likely to increase demands on transportation or public
services and utilities?
Adoption of the CFHMP would not be likely to increase demands on transportation or public
services and utilities Implementation of projects consistent with the CFHMP would likely
have an effect on existing utilities such as the Yakima Regional Wastewater Treatment Plant
(WWTP) outfall. With implementation of levee set backs along the east side of the Yakima
River the outfall for the WWTP will need to be relocated or a different method of treatment
will need to be incorporated.
Proposed measures to reduce or respond to such demand(s) are: None Further
environmental assessment and identification of potential mitigation projects is needed
Assessment will need to be funded and mitigation will need to be constructed on a time
frame that ensures that concerns about the WWTP's outfall are addressed
7 Identify, if possible, whether the proposal may conflict with local, state, or federal laws
or requirements for the protection of the environment
The CFHMP describes a coordinated approach to flood hazard management within a
complex interagency and inter -jurisdictional context.
Implementation of projects and policy proposals consistent with the CFHMP will require
future assessment for environmental significance, regulatory consistency, and policy
preferences of relevant jurisdictions and agencies
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Appendix F
IDENTIFICATION AND INTEGRATION OF POLICIES FOR CITY OF
YAKIMA
RECEIVED
APR 0 8 2008
CITY OF YAXIMA
PLANNING Diy.
This CFHMP recognizes the existing policies for flood hazard management within the
City of Yakima Urban Area as set forth in the Yakima Urban Area Comprehensive Plan
2025 ("Plan 2025") and also recognizes the existing development regulations set forth in
the Yakima Municipal Code ("YMC"). The policies set forth in Plan 2025 and the
development regulations set forth in the YMC are incorporated by this reference as the
only land use regulations and restrictions on construction activities of the CFHMP that
are applicable to and binding on the City of Yakima for all purposes of Ch. 86.12 RCW.
•
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y
ITEM TITLE:
BUSINESS OF THE CITY COUNCIL
YAKIMA., WASHINGTON
AGENDA STATEMENT
Item No.
For Meeting Of May 6, 2008
Resolution of the City of Yakima, Washington, adopting the Upper
Yakima River Comprehensive Flood Hazard Management Plan RM
107-128 June 2007 Update, Including New Appendix F.
SUBMITTED BY William R. Cook, Director Community & Economic Development
CONTACT PERSON/TELEPHONE. Jeff Peters, Assistant Planner - 575-6163
SUMMARY EXPLANATION:
The Upper Yakima River CFHMP was adopted by the Board of Yakima County
Commissioners on June 19, 2007. The CFHMP describes the studies, findings, and
recommendations of the Yakima Countywide Flood Control Zone District (FCZD) for
flood hazard prevention and floodplain restoration along as more fully described in the
CFHMP.
The CFHMP describes a coordinated approach to flood hazard management within a
complex interagency and inter -jurisdictional context. Implementation of projects and
policy proposals that are consistent with the CFHMP will require further assessment for
environmental significance, regulatory consistency, and policy preferences of the
relevant jurisdictions and agencies.
CONTINUED ON NEXT PAGE
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Contract Mail to (name and address)
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Funding Source
APPROVAL FOR SUBMITTAL:
City Manager
STAFF RECOMMENDATION Approve resolution
BOARD RECOMMENDATION None
COUNCIL ACTION
As a statutorily prescribed comprehensive flood control management plan, the CFHMP
will, upon adoption by the City of Yakima, become binding.(RCW 86 12.210). Any land
use regulations and restrictions on construction activity contained within the CFHMP
that are applicable to the City of Yakima will become the minimum standards of the City
and may supplant existing City of Yakima regulations and standards.
Overall, the City's proposed adoption of the CFHMP brings with it risks that are difficult
to quantify. The risks identified below are not exclusive, in part because the CFHMP
itself contains ambiguities which make its effect difficult to fully analyze.
The proposed resolution of adoption is intended to minimize potential risks. A risk
analysis of the CFHMP adoption is provided in the form of the attached April 24, 2008
memorandum prepared by outside legal counsel, Kenneth W. Harper
With regard to environmental review, Yakima County issued a SEPA Final MDNS for
the CFHMP in July of 2005. The City in reliance on the County's environmental
process issued a SEPA Notice of Application and Environmental Review on April 14,
2008 noting an expectation that a DNS will likely be issued. The public comment period
for the City's application ends May 5, 2008. A SEPA determination will follow the close
of the comment period Staff will report the nature of comments received and the
SEPA determination at the May 6 meeting.
Yakima County is the responsible agency for floodplain planning in the County As
such the City has relied heavily on the expertise of County staff in this effort. Staff has
worked diligently with County officials for the past year to improve consistency between
the CFHMP and existing City policies and regulations. A review of City floodplain
regulations and policies by Yakima County planning staff concluded that existing City
standards are consistent with the CFHMP. Given the effort, progress, and
understandings reached through this process staff • recommends adoption of the
CFHMP.
•
•
•
Draft Upper Yakima Comprehensive Flood Hazard Management Plan Amendment
CHAPTER 8.
ANALYSIS OF FLOOD MITIGATION ALTERNATIVES
During the CFHMP planning process, Advisory Committee members identified a variety of
flooding issues and concerns and proposed a range of potential solutions. This chapter
presents identified flooding issues, analysis of potential mitigating alternatives, and preferred
alternatives following the approach described in Chapter 7.
Each flooding issue is presented as either region -wide, specific to a river reach, or affecting
areas outside the CFHMP study area. Region -wide issues apply throughout the study area and
include regulatory issues, general trends in flood patterns, issues associated with operation and
maintenance of flood control facilities, and land use issues. River reach issues identify specific
areas within a river reach that continually experience flood damage or that have been identified
as a flooding concern. Flooding issues outside the CFHMP study area are additional concerns.
Each flooding issue was given a label indicating geographic area and issue number, and those
with specific locations were plotted on Figure 8-1. For example, label RW1 refers to region -wide
issue number one, UR1 refers to issue one in the upper reach (Yakima Canyon to Selah Gap),
MR2 refers to issue two in the middle reach (Selah Gap to SR 24 Bridge), and LR1 refers to issue
one in the lower reach (SR 24 Bridge to Union Gap). Issues outside the study areas are
identified as OSA.
Through a ranking process, Advisory Committee members assigned each flooding issue a
priority (shown below in parenthesis). The issues are presented below and in Table 8-1 in order
of priority. Related issues are combined, and discussed as a single issue.
For the amendment, flooding issues have been reprioritized based on the likelihood of near
term projects (such as SR 24 bridge replacement), changed conditions since the original plan
was drafted (such as the purchase of large areas of floodplain by the BOR), or additional
information or studies which were not available to the original advisory committee (such as the
LIDAR data, the Stanford et al studies, the analysis by Lorang, or the Floodplain Consistency
Report for SR 24).
TABLE 8-1.
ADVISORY COMMfFI'EE RANKING OF FLOODING ISSUES
ID
Flooding Issue Rank
LR5 Additional Flood Protection Below SR 24 Bridge
MR5 Yakima Beech Street Gravel Pit Levee
MR5 Development near Hartford Road
RW1 Floodplain Mapping
UR2 Development of Pomona, East Selah, Selah Areas 5
1
2
3
4
8-1
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
RW13 Funding for Flood Control Work and Restoration 6
Proj.
RW11 Inconsistent Land Use and Zoning in the 7
Floodplain
RW6 Public Disclosure of Floodplain Status 8
RW12 Protection of State and County Roads 9
RW3 Channel Migration 10
RW9 Diversity of Opinions Relating to River 11
Management
RW4 Flood Hazard Ordinance 12
LR2 Protection of Private Property below SR24 13
LR3 Increased Flood Elevation near Union Gap 14
RW14 Use of Nonstructural versus Structural Flood 15
Control
RW2 Loss of Fisheries Habitat and Riparian Areas 16
MR1 Gordon Lake Levee 17
LR1 Erosion of Agricultural Land 18
RW17 Existing Structures in the Floodplain 19
RW8 County Policy on Flood Hazard Management 20
RW16 Operation and Maintenance of Flood Control 21
Facilities
LR4 Development near Riverside Road 22
RW10 Acquisition / Preservation of Floodplain Open 23
Space
RW19 Flood Warning and Emergency Response 24
RW18 Community Rating System 25
UR1 Erosion of Agricultural Land 26
RW15 Use of GIS Data 27
8-2
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
UR5 East Selah Gravel Pit Levee 28
RW5 Revision and Consistency of Critical Areas 29
Ordinance
OSA Continued Flood Damage Outside CFHMP Area 30
MR4 Right Bank Yakima River Levee near Boise Cascade 31
RW7 Flood Insurance and Public Education 32
LR6 Spring Creek Backwater Flooding 33
MR3 KOA Campground Levee 34
MR7 Flood Damage to Robertson Landing 35
MR8 Borrow Pit Levee Upstream of Terrace Heights 36
Bridge
MR6 Flood Damage to Greenway Path near Boise 37
Cascade
UR3 Flood Damage to Harlan Landing
Inundation of Elks Golf Course
UR4
38
39
TABLE 8-1.
AMENDED CFHMP RANKING
ID
Flooding Issue Rank
LR5 Additional Flood Protection Below SR 24 Bridge
MR5 Yakima Beech Street Gravel Pit Levee
LR3 Increased Flood Elevation near Union Gap 3
LR7 Capture of Edler Ponds
MR5 Development near Hartford Road 5
RW1 Floodplain Mapping 6
UR2 Development of Pomona, East Selah, Selah Areas 7
RW13 Funding for Flood Control Work and Restoration 8
1
2
4
Public Disclosure of Floodplain Status
Flood Hazard Ordinance
Existing Structures in the Floodplain
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
RW11
RW6
RW3
RW9
RW4
LR2
RW14
RW2
MR1
LR1
RW17
RW8
RW16
LR4
RW10
RW19
RW18
UR1
RW15
UR5
RW5
Proj.
Inconsistent Land Use and Zoning in the 9
Floodplain
RW12 Protection of State and County Roads
10
11
Channel Migration 12
Diversity of Opinions Relating to River 13
Management
Protection of Private Property below SR24
Use of Nonstructural versus
Control
Structural
Flood
14
15
16
Loss of Fisheries Habitat and Riparian Areas 17
Gordon Lake Levee 18
Erosion of Agricultural Land 19
20
County Policy on Flood Hazard Management 21
Operation and Maintenance of Flood Control 22
Facilities
Development near Riverside Road 23
Acquisition / Preservation of Floodplain Open 24
Space
Flood Warning and Emergency Response
Community Rating System
Erosion of Agricultural Land
Use of GIS Data
East Selah Gravel Pit Levee
Revision and Consistency of
25
26
27
28
29
Critical Areas 30
8-4
Inundation of Elks Golf Course
Aggradation upstream of SR 24 Bridge, Flood damage to SR 24 Bridge,
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
LR5 —
Ordinance
OSA Continued Flood Damage Outside CFHMP Area 31
MR4 Right Bank Yakima River Levee near Boise Cascade 32
RW7 Flood Insurance and Public Education 33
LR6 Spring Creek Backwater Flooding 34
MR3 KOA Campground Levee 35
MR7 Flood Damage to Robertson Landing 36
MR8 Borrow Pit Levee Upstream of Terrace Heights 37
Bridge
MR6 Flood Damage to Greenway Path near Boise 38
Cascade
UR3 Flood Damage to Harlan Landing 39
UR4
Additional flood protection below SR 24 bridge (1)
Original Priority: 1 of 39
Amendment Priority:1 of 39
Problem Definition
Diking District No. 1 wishes to provide additional flood protection to landowners along the
eastern side of the Yakima River downstream of SR 24 bridge. FEMA floodplain delineation
predicts extensive inundation during the 100 -year flood event and a depth of flooding
exceeding 5 feet within residential areas along Riverside Road. During February 1996 there
was little flooding behind the levee due to flood levels being lower than predicted and to some
emergency work. The Diking District has proposed raising an existing riverbank levee to the
100 -year level of protection. The existing levee extends along the left bank from SR 24 bridge
downstream approximately 10,000 feet. Raising the existing levee would accomplish the
following:
8-5
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Provide additional flood protection to existing property, structures, and gravel
resources
• Possibly remove property from the regulated floodplain.
Raising the existing levee could provide additional protection to private land owners.
However, care must be taken to minimize any negative impact on environmental resources,
particularly fisheries, and nearby properties that may suffer additional flooding.
The configuration of the levees and the SR 24 bridge have resulted in a constriction in the area
of the bridge itself. Presently, channel and floodplain elevations interior to the levee system
are in places 6-10 feet higher that the natural floodplain elevations outside the levees ((Fig. A8-1
and A8-2). A recent analysis of stream power (Lorang 2001) shows that the combination of
gravel accumulation which narrows the channel, and increased slope, has resulted in high
levels of available energy to transport sediment (Figure A8-3), or specifically in this reach, areas
of high energy associated with levee erosion and bridge pier scour which occurred in the 1996
flood. Further aggradation upstream of the bridge will aggravate those existing problems, as
well as associated problems such as raising of the local water table; accelerated scour,
downcutting of the riverbed, and associated erosion of the levee and water table fall
downstream of the bridge, as well as reduction in the capacity of federal levees to control the
base flood.
Associated with the aggradation and configuration of the levees is a scour problem at the SR 24
bridge. Essentially, several of the bridge piers were constructed on shallow footings. With
movement, downcutting of the channel, and increased energy through the bridge opening,
several of the SR 24 bridge piers are in danger of failure during fairly small and frequent flood
events. Currently, the SR 24 Bridge is listed as "Scour Critical" by WSDOT and is monitored
during and after all flood events for scour at the piers. On 5 separate occasions, the WSDOT
has had to perform emergency (i.e. outside normal hydraulic season work window)
stabilization of the bridge piers by installing riprap and grouting to support the footings of
these piers.
8-6
1
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
1
1
1
I ±,,g
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1020.000
1018.000
1016.000
1014.000
1012.000
1010 000
1008.000
1006.000
1004.000
1002.000
Cross Section #13
0.000 500.000 1000.000 1500 000
Distance
Floodplain in
Sportsman's
Sate Park
000 2500.000
Rising
Floodplain inside
Levees
3000 000
—+— ELEVATION
Yakima
River
Channel
Figure A8-2. Aggradation (Stream Bed and Floodplain Rise) at Sportsman's State
Park. The Cross section is derived from LIDAR data and shows on the left (east)
side of the graph the floodplain elevation in the State Park, outside of the levees.
This is the level of the floodplain prior to construction of the levees in 1947. Inside
the levees, the floodplain has aggraded 6-8 feet in places. As gravel accumulates
in the floodplain, the active channel is forced against the levee, increasing stream
power and erosion of the levee face. As aggradation proceeds, the levees are in
danger from over topping (due to loss of conveyance) and erosion or undercutting
(due to confinement of the stream against the levee face).
8-8
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
'jy Power (Std Dev)
'� • -1 - O Std. Dev. ;
r Mean � ,
a
-??_ «'+ --j' yi:'►�.� 0-1 Std Dev. .i
nr;'' zt "�:4;Fy �-* �+ rag 1 - 2 Std. Dev.
f •., ' �\ ' t 2 - 3 Std. Dev.
5, 0x'1.• N. > 3 Std. Dev.
1 _�i . :a‘
500
500 Meters
N
A
Figure A8-3. Stream Power Graphic. Red indicates higher stream power and is
associated with areas of Ievee erosion or bridge scour. Note that the areas of high
energy are relatively small, that most of this reach actually has fairly low levels of
energy, and that high energy is concentrated along the levee and at the bridge
opening. From Stanford et al 2002.
8-9
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Discussion of Alternatives
Additional Flood Protection Below SR 24 Bridge
To evaluate the potential for flood hazard reduction below SR 24 Bridge, the following levee
alternatives were examined:
• Strengthen the existing levee but maintain its current elevation
• Raise the existing riverbank levee to provide 100 -year protection, extending
2,000 feet downstream of SR 24 bridge
• Raise the existing riverbank levee to provide 100 -year protection, extending
approximately 10,000 feet downstream of SR 24 bridge
• Construct a 100 -year setback levee along Blue Slough, extending
approximately 2,500 feet downstream of SR 24 with no modification to the
existing levee
• No modifications to the existing levee (No Action).
Levee alternatives were evaluated using a hydraulic computer model (HEC -2), the computer
model used by FEMA to define the regulatory floodplain. FEMA HEC -2 data files were
obtained from the COE and modified to reflect changes in river hydraulics caused by levee
modifications. Several scenarios were simulated to determine the impact on flood elevations
and floodplain boundaries. Objectives of the computer simulations were as follows:
• Determine how high the existing riverbank levee must be raised to provide
100 -year protection
• Determine the level of protection provided by the existing levee
• Determine amount of flow, depth of flooding, and floodplain boundaries east
of the existing levee if the levee was overtopped
• Examine changes in floodplain boundaries and flood elevations if a 100 -year
levee extended 2,000 feet downstream of SR 24 bridge (this was previously
evaluated by the COE)
• Examine changes in floodplain boundaries and flood elevations if a 100 -year
levee extended 10,000 feet downstream of SR 24 bridge
• Examine changes in floodplain boundaries and flood elevations if a 100 -year
setback levee was constructed along Blue Slough.
Level of Protection for Existing Levee
Computer analysis completed in 1995 revealed that the left bank levee existing at that time
should provide approximately a 25 -year level of protection with no freeboard. Therefore, at
flows greater than 35,000 cubic feet per second (cfs), a 25 -year event, the existing left riverbank
levee would be close to overtopping. Overtopping would begin at a low point approximately
2,000 feet downstream of SR 24. For flows greater than 35,000 cfs, the area behind the levee
(i.e., the left overbank) would be used to convey floodwaters.
8-10
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
For a 100 -year flood event (56,300 cfs at Parker), an additional 21,300 cfs must be conveyed in
the channel and behind existing levees. To confine the 100 -year flood flow within the left bank
levee, the levee would need to be raised between 1.5 and 6.0 feet to provide 3 feet of freeboard
(specific increases in elevation depend on the location along the levee).
Emergency modifications to the levee were made in response to the February 9, 1996 flood
(peak flow reached approximately 56,000 cfs). There were concerns that the levee would
overtop and possibly fail. The emergency construction kept floodwater contained within the
main channel and prevented the levee from overtopping. The emergency work allowed the
structure to provide greater protection than predicted in the hydraulic analysis.
Review of Existing Hydraulic Conditions
Yakima River hydraulic conditions were reviewed to assess the accuracy of existing floodplain
boundaries. This involved reviewing the hydraulic model FEMA used to determine the revised
preliminary regulatory floodplain (FEMA 1995).
Reviewing FEMA's computer model revealed that the existing left bank levee below SR 24
bridge was not represented in the data. This is standard practice if the levee does not meet
FEMA elevation requirements to confine the 100 -year flood flow with 3 feet of freeboard.
Therefore, FEMA floodplain boundaries were determined as if the levee did not exist. To
examine if this overestimated the extent of floodplain boundaries, computer model runs were
performed with the left riverbank levee in place. The analysis used surveyed levee elevations
collected prior to the February 1996 flood. The following scenarios were simulated:
• Allow the levee to overtop without any structural failure
• Allow a 1,000 foot levee failure at the lowest elevation location without a
permanent channel change as a result of the failure.
Allowing the existing left bank levee to overtop or fail during a 100 -year event results in
floodwaters being conveyed within the left overbank. Water surface elevations and floodplain
boundaries were estimated using these predicted overbank flows. Table 8-2 displays predicted
water surface elevations for estimated flow rates conveyed in the left overbank. If the levee
were overtopped with no structural failure, an estimated 8,500 cfs would be conveyed within
the left overbank. If the levee failed at its lowest elevation, an estimated 12,000 cfs would be
conveyed within the left overbank. Both scenarios convey considerably less flow than
predicted by FEMA's model.
Compared to FEMA's flood elevations, including the existing levee in the computer model
results in higher water surface elevations in the channel but lower flood elevations within the
left overbank. Therefore, if the existing 25 -year levee overtopped without failure during a
100 -year event, left overbank water surface elevations are estimated to be 0.9 to 2.4 feet lower
than those predicted by FEMA. However, water surface elevations in the main channel were
predicted to be 0.6 to 2.0 feet higher. The increase in estimated channel water surface
elevations represents less flooding in the left overbank than FEMA estimated, but more
flooding on the right overbank than shown by FEMA.
Similarly, if the left bank levee failed, left overbank water surface elevations are predicted to be
0.2 to 1.9 feet lower than those predicted by FEMA. However, water surface elevations in the
main channel would be 0.2 to 1.7 feet higher. Compared to FEMA flood predictions, the levee
failure scenario also represents a decrease in flooding in the left overbank and higher flood
elevations in the right overbank. Therefore, representing hydraulic conditions with the existing
8-11
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
25 -year levee generally displays a decrease in flood hazard within the left overbank in
comparison to hydraulic conditions without the levee as modeled by FEMA (i.e. areas adjacent
to and downstream of the City of Yakima WWTP.
Levee Alternatives
Hydraulic conditions were modified in the computer model to represent the various levee
alternatives listed above. The various model simulations predict changes in water surface
elevations, floodplain boundaries, and assessed value protected relative to the preliminary
revised FEMA floodplain conditions (Figures 8-2 and 8-3).
Yakima County
UPPER YAK/MA RIVER CFHMP
KCM
El Setback Levee
p 10,000' Levee
• 2,000' Levee
p Existing Levee
I Average Channel
Velocity during flood(fps)
l (
Parcels Protecte
Assessed Value
Protected ($) 111
1 Floodplain Area
(acres)
I
I I I I I I
-60% -40% -20% 0% 20% 40% 60%
Percentage Change (relative to FEMA's preliminary revised floodplain)
Figure 8-3.
INCREMENTAL CHANGES FOR VARIOUS LEVEE CONDITIONS
Existing Levee: Integrating a structurally sound 25 -year left riverbank levee into the existing
river hydraulic conditions shows that flood hazards are not as severe as those represented on
FEMA floodplain maps. A 25 -year levee reduces floodplain area by 21 percent, and decreases
assessed property value within the floodplain by 13 percent from FEMA floodplain conditions.
In addition, the 25 -year levee reduces the potential for catastrophic failure and the need for
emergency flood fighting that a 100 -year levee would create. (NOTE: This option would not
remove any property from the flood plain.)
8-12
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
2000 Foot 100 Year Levee: Raising the existing left riverbank levee for 2,000 feet downstream of
SR 24 bridge to provide 100 -year protection would reduce the floodplain area by 1 percent and
increase the assessed property value within the floodplain by 7 percent from FEMA floodplain
conditions. Assessed property value within the predicted floodplain increases due to high
value property becoming inundated on the right bank. This alternative would also increase
velocities in the river channel and reduce potential fish habitat. (NOTE: This analysis does not
consider any structure down stream of the 2000 ft structure)
10,000 foot 100 Year Levee: Raising the existing left riverbank levee for 10,000 feet downstream of
SR 24 Bridge to provide 100 -year protection would reduce the floodplain area by 46 percent and
decrease the assessed property value within the floodplain by 12 percent from FEMA
floodplain conditions. Floodplain area decreases on the left bank, but increases on the right
bank, where assessed property values are higher. This alternative also increases velocities in
the river channel and reduces potential fish habitat.
Setback Levee: Constructing a 100 -year setback levee 2,500 feet downstream of SR 24 along Blue
Slough would provide protection to development near Riverside Road, reduce the floodplain
area by 24 percent, and decrease assessed property value within the floodplain by 15 percent
from FEMA conditions. However, this alternative increases the right overbank flooding and
reduces potential future fish habitat. The existing levee is not represented in this hydraulic
analysis. Analysis is representative of potential beneficial and adverse effects of the
alternatives, and more analysis must be performed before a final selection is made.
Replacement of SR 24 Bridge
The WSDOT is proposing the replacement of the SR 24 Bridge due to improve traffic capacity of
the bridge and adjacent portions of SR 24 in the Yakima UGA, and due to scour of the bridge
piers which occurs at flood discharges at and above the 1 -year flood (WSDOT, 2003).
Currently the WSDOT is proposing the replacement of the SR 24 bridge with a 4 lane structure
that either:
• Spans the river with a bridge that is approximately 600 feet in length, similar to the
existing condition, or
• Spans the river with a 1400 to 1600 foot bridge that begins extends from
approximately Keys Road to 200 west of the existing SR 24 abutment.
An Environmental Assessment has been prepared for the project by WSDOT, along with an
analysis of the current floodplain conditions upstream and downstream of SR 24 (Park, 2003).
The basis for the longer bridge alternative is that the current configuration of the levees
upstream and downstream of the bridge, inclusive of the bridge itself, is leading to aggradation
upstream of the bridge, and degradation downstream. The aggradation upstream of the bridge
has resulted in lessening of the conveyance capacity upstream of the bridge. The levee system
was originally constructed to control the 200 -year flood, it now controls the 100 -year flood
despite having been raised twice (in 1971 and 1982) to bring it into conformance with Corps
requirements. If the SR 24 bridge is replaced in kind, aggradation will likely continue into the
future, resulting not only in increased operational costs for maintenance of the levee but also:
S-13
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Increased Stream Power and erosion of the levees upstream and downstream of SR
24, and erosion of the bridge abutments themselves, due to increase in local slopes
and confinement of the stream channel.
• Further increases in the elevation of the water table upstream of the bridge, and
lowering of the water table downstream of the bridge
• Starvation of downstream reaches of sediment, resulting in hazard to infrastructure
downstream.
Additional Considerations
Prior to selecting an alternative, additional considerations require examination of factors other
than changes in water surface elevations, floodplain boundaries, channel velocities, and
assessed value of property protected. Specifically, construction cost, the impact on
environmental resources, the regulatory environment, and ownership of the flood protection
facility must also be considered.
The proposed riverbank levee is currently located in the regulatory floodway, which is reserved
to convey flood flows without further encroachment. If a community proposes to permit
encroachments into the adopted regulatory floodway resulting in any increase in flood levels,
as would building the proposed levee, and chooses to continue to participate in the National
Flood Insurance Program, the following regulatory conditions or actions must be met
(44 CFR 65.12):
• Request conditional approval of map change and submit appropriate initial fee
• Evaluate alternatives that would result in zero rise in the base flood elevation,
demonstrating why these alternative are not feasible
• Document individual legal notice to all affected property owners within and
outside the community, explaining the impact of the proposed action on their
property
• Obtain concurrence of the Chief Executive Officer of any other communities
affected by the proposed action
Certify that no structures are located in areas that would be affected by the
increased base flood elevation
Request revision of base flood elevation determination according to the
provisions of 44 CFR 65.6—Revisions of base flood elevation determinations
A request for floodway revision in accordance with the provisions of
44 CFR 65.7—Floodway revisions
Upon receipt of conditional approval of map change and prior to approving
the proposed encroachments, provide evidence of the adoption of floodplain
management ordinances incorporating the increased base flood elevations or
revised floodway reflecting the post -project condition
8-14
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
• Upon completion of the proposed encroachments, provide as -built certification
in accordance with 44 CFR 65.3 — Requirement to submit new technical data.
A final map revision will be initiated upon receipt of such certifications.
The proposed riverbank levee could also have an impact on environmental resources,
specifically fisheries. While a detailed impact assessment will not be performed here, it should
be recognized that the Yakima River supports populations of spring and fall Chinook salmon,
rainbow trout, and steelhead. Chinook salmon currently spawn and rear in the vicinity of the
proposed levee. Raising the riverbank levee could further decrease the potential for rearing
habitat in an already limited river system. Raising the riverbank levee could also increase
channel velocities during a significant flood, resulting in additional scour and erosion.
Overall public costs and benefits were also considered in evaluating the levee alternatives.
Planning level costs and benefits are summarized in Table 8-3. Cost estimates for levee
improvements include construction items, engineering, legal and administration, and a
30 percent construction contingency. Previous COE cost estimates (COE 1978), inflated to
current dollars, were also used. Incremental benefits were evaluated by determining the
assessed property value removed from the floodplain, therefore providing a measure of
property value protected. Based on this analysis, the 2,000 -foot levee alternative gives a
negative benefit -to -cost ratio. The negative benefit results from an increase in the extent of the
floodplain and the value of property contained within the floodplain. All other alternatives
result in positive benefits, that is, valued property was removed from the floodplain. The
setback levee alternative resulted in the largest benefit -cost ratio, and the 10,000 -foot levee
resulted in the smallest. Actual damage prevented will be less because the properties will not
be completely destroyed.
TABLE 8-3.
COSTS AND BENEFITS ASSOCIATED WITH LEVEE ALTERNATIVES DOWNSTREAM OF SR 24
Alternative
Incremental Incremental Benefit/ Cost
Cost a Benefit h Ratio
Restore structural integrity of existing levee; $583,000 $1,942,600
maintain current top elevation
Raise existing left riverbank levees to provide c ($1,056,100)
100 -year protection, extending 2,000 feet
downstream of SR 24 bridge
Raise existing left riverbank levee to provide $1,400,000 $1,745,800
100 -year protection, extending approximately
10,000 feet downstream of SR 24 bridge
Construct 100 -year setback levee along Blue $624,000 $2,166,700
Slough, extending approximately 2,500 feet
downstream of SR 24 bridge
3.3
negative
1.2
3.4
a. Based on planning level cost estimates or previous COE estimates (COE 1977) inflated to current
dollars.
a. Estimated by calculating the increase in assessed value of property protected relative to the
existing FEMA floodplain. Actual damage prevented will be less.
a. No cost estimate due to negative benefit.
8-15
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
The final consideration is who will be the lead agency for construction and maintenance of the
new levee facility. The Diking District is currently taking the lead role on the proposed levee.
The District would need to secure resources for design, construction, maintenance, and flood
fighting, or develop cost -share agreements with the County. Prior to project acceptance, a
definitive funding mechanism and maintenance program need to be developed.
Updated information:
BOR,/YRBWEP: Since 1999 the United States Bureau of Reclamation (BOR) has been acquiring
property in the floodplain below the SR 24 Bridge in implementation of the Yakima River Basin
Water Enhancement Project (YRBWEP), which was passed by Congress in 1994. The BOR's
goals were to acquire/protect/restore valuable habitat for salmonids as well as the water rights
associated with these parcels. Based on research in the Yakima River Basin funded by BOR
(Stanford and Snyder 2001, Stanford et al. 2002) the "Union Gap Reach" between Selah and
Union Gaps was selected as the mainstem reach that is best suited for restoration of salmonid
habitat. The most valuable habitats in this reach are in the lower portions below SR 24, and
Figure A8-4 shows the location of these BOR purchases, as well as purchases by the Yakama
Nation, which were for similar purpose. Given the effect that the design and location of a
replacement SR 24 bridge would have on the BOR's goals for restoration and protection of
habitat in the lower Union Gap Reach, the BOR has been active in advocating a longer span to
allow for more floodplain restoration at and downstream of SR 24. Depending on the
configuration of the new bridge, the BOR is willing to actively pursue more property
acquisition in this area to maximize floodplain restoration. Much of the economic analysis
below which looks at the effects of construction of a new 100 -year levee near Blue Slough has
been superceded by the early acquisition of most of the property which would be affected by
levee removal and setback. An economic analysis performed today would likely show a much
greater positive benefit to levee setback due to the greatly reduced negative economic effects on
private property.
8-16
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Bureau of
Reclamation
Properties
Union Gap
Figure A8-4 Bureau of Reclamation ownership and other Public ownership in the
Gap to Gap Reach.
SR 24 Bridge: As discussed previously, WSDOT is preparing to replace the SR 24 bridge.
Depending on the bridge design and configuration, the levees may be set back or removed in
several different configurations. Any levee setback or reconfiguration should incorporate the
proposed SR 24 bridge replacement. Since the SR 24 Bridge currently acts as the most
downstream point of the Federal Flood Control Project, modification of the SR 24 Bridge will
require approval by the Corps of Engineers, since removal of that abutment modifies the
Federal Project. Since any new levee which is designed to meet a 100 -year standard will need
to be designed in relation to the upstream Federal Project, it is appropriate to involve the Corps
in the design process for a setback or reconfiguration of the DID #1 levee downstream of SR 24,
as well as changes in the Federal Levee project upstream of SR 24.
Central Pre- Mix Mining Proposal: Central Pre -Mix (CPM) has received zoning approval for a
new gravel mine and processing facility on property CPM owns on Riverside Road, east of the
Yakima River. The proposed mine pits will be over 1200 feet from the Yakima River, and as
additional mitigation, CPM has committed to setback of a portion of the DID #1 levee on their
property, and to dedicate a 197 acre area west of the proposed setback levee as a floodplain and
wildlife "enhancement area" (see Figs A8-5 and 6). Any levee setback or reconfiguration
should also take advantage of the CPM proposal as well.
8-17
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
In addition, the Newland pit, which was active during the formulation of the original CFHMP,
has ceased operation, and is in the process of being reclaimed by CPM. The configuration and
depth of these pits make them good candidates for incorporation back in to the floodplain of
the Yakima River.
SR 24
Proposed Central
Premix East Valley
Mine Properties
Figure A8-5 Proposed Central Pre -Mix East Valley Gravel Mine and Associated
Properties
8-18
City of Yakima WWTP: As stated above, the configuration of the levees and SR 24 bridge
concentrates the flow of the river in a relatively small area, which leads to aggradation
upstream of the bridge, high scour and energy at the bridge itself, and erosion downstream of
the bridge. The conditions downstream of the bridge are favorable for the City's Wastewater
Treatment Plant outfall, which is located in this area. The concentration of flow means that the
main flow of the river is always located at the WWTP outfall, and the relatively high velocities
and high turbulence of this steep and confined section ensure that the WWTP effluent is
rapidly and efficiently diffused into the river. The standard the WWTP effluent must meet is
based on State water quality standards, and a statistical low flow (the 7 day low flow which
occurs with a frequency of 10 years), to ensure that even at very low flows the water quality
standards are not violated. Changes to the configuration of the bridge and levee system
upstream can be expected to change the hydraulic conditions at the outfall, with a very high
probability that the river channel will begin to move if the levees are relocated. This would
result in the outfall no longer being located in the river, the outfall being buried as the river
recovers to a more natural elevation, or reduced flow and turbulence at the outfall, any of
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Enhancement Area
Current DID # 1 levee
Mining
Area
Figure A8-6 Proposed Enhancement area and current location of Diking
Improvement District #1 Levee, Proposed Central Pre Mix East Valley Mine
8-19
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
which would result in violation of water quality standards and/or the City's permit from the
Department of Ecology which allow the WWTP to discharge to the river.
The WWTP serves the entire urbanized area of Yakima, including the City of Yakima, the City
of Union Gap, and the Terrace Heights area and it is critical that this facility continue to
function into the future, in conformance with state water quality standards.
River Bed and Water Table Rise Upstream of SR 24, River Bed and Water Table Lowering
Downstream of SR 24. Figure A8-7 shows the relative elevations of the water surface of the
river, the floodplain inside the levee system, and the floodplain outside of the levee system.
Upstream of SR 24, the water surface elevation is above the elevation of the floodplain surface
outside the levees in several locations. Analysis of aerial photos and conversation with
personnel at the Arboretum and Sportsman's State Park indicate that the water table associated
with the river has also risen. On the Arboretum (west) side of the river, this has resulted in
vegetative change (die off of trees) in a wetland that is located in an old river meander, and a
similar die off of some trees on the State Park side. On both sides of the river, there are
"floodgates" through the levee system which are designed to be opened when floodwaters
accumulate outside of the levee system, and need to be drained toward the river. On the
Arboretum side of the river, these "floodgates" also serve as the outlet of Buchanan Lake
(which is the water table exposed to the surface) during most of the most of the year, and the
"floodgates" are closed during flood events to prevent floodwaters from backflowing during
the event.
8-20
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
1025
10'6
1300
995
990 `-
985 985
980
River Water Surface
well Below Natural
floodplain elevation
SR 24 Profiles
Floodplain inside
levee higher than
floodplain outside
levees
1'
Flow Direction
SR 24 Bridge
—4— Floodplain
Inside Lee
—X— WSE
452000 453000 454000 455000 456000 457000 458000 459000 460000 461000 462000
Distance
Figure A8-7. Change in bed elevation upstream and downstream of SR 24. This is a
longitudinal profile of the water surface of the Yakima River, the floodplain inside
the levees, and the floodplain outside the levees derived from LIDAR data. The SR
24 Bridge is in the middle of the graph where the blue spike is. Note how the
elevation of the cyan line (water surface elevation) relative to the blue line
(floodplain outside the levees) changes as the river moves through the bridge. The
channel is rising upstream, and lowering downstream.
The rise of the riverbed and water table are problematic for several reasons. Currently, the
Buchanan Lake drain must be annually maintained and deepened because the river bed plugs
the outlet (i.e. the river bed is now above the elevation of the floodgate), and the gate is not
very effective as a drain as a result. During the 1996 flood, Buchanan Lake rose, but could not
drain to the river and instead in drained through the Arboretum, and into Nob Hill Auto
Wrecking's Yard, which was flooded for several days. If the river bed and water table
continue to rise in this area, this type of flooding (i.e. flooding outside of the levees which
cannot be controlled) will become more frequent, the efficiency of the Buchanan Lake drain will
continue to be reduced and the lake and water table elevation will rise (which effects I-82,
Central Premix, the Arboretum and other properties west of I-82), and Sportsman's State Park
8-21
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
and the Arboretum will continue to lose large trees which are of high recreational and public
value.
Downstream of SR 24, lowering of the water table was initially associated with the gravel
mining operations at the Newland Pit on the east side of the river. During mining,
groundwater was pumped out of the pits (usually during summer and fall), this locally lowered
the water table in the vicinity of the pit. Due to the near surface geology of the area (for a
good description see the CPM EIS for the proposed East Valley mine; Brown, 2002), this
resulted in a loss of water to the root zone of adjacent cottonwood trees, and their death. Since
the mining activity has now stopped, the water table has not recovered, and remains at the
same elevation as the surface of the river (see Fig. A8-8 and A8-9). Recovery of the natural
riparian zone in this area will probably not occur unless the water table rises to its pre -mining
and pre -river downcutting elevations. Based on the soils exposed in the pit walls of the mining
area, the current water table is approximately 5 feet lower in the spring, and can be expected to
continue to lower if the hydraulic/sediment routing conditions in this reach remain similar to
their current condition.
Figure A8-8 Cross -Section location at the Newland Pit.
8-22
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
1302 000
1300.000
996.000
996.000
eY 994.000
W
992 000
990.000
966.000
986.000
Cross Section # 18
Newland Pit
Water Surface
0.000
200 000
400 000
600.000
Distance
800.000
900.000
I+ ELEVATION
Yakima
River Water
Surface
400.000
Figure A8-9 LIDAR Generated Cross Section Note the similarity in elevation
between the water surface elevation of the river and of the water level in the pit.
Preferred Alternative
Based on the above analysis and observations made during the February 1996 flood, a
two -phased alternative is proposed. The first phase will provide additional flood protection
not displayed in the preliminary revised FEMA floodplain maps at a minimal cost and impact
to environmental resources. The final phase will allow the river to recapture some of its natural
floodplain, provide additional storage for floodwaters, enhance future fisheries habitat, protect
property near Riverside road and limit the impact of flooding on the western bank of the river.
First Phase
Strengthen the existing levee downstream from SR 24 to protect existing gravel operations, but
maintain the current top elevation. . Potential structural enhancements could include the
following:
• Remove poorly graded levee fill and replace with compacted, well -graded fill
• Flatten embankment slopes
Second Phase
• Following gravel extraction, implement a reclamation plan that restores some of
the floodplain s natural function. This could include modifying the existing
8-23
Amendment Preferred Alternative
■ Improve sediment transport through this reach. This will:
Recommended Actions;
Practically, achieving that management will probably require multiple actions in different
areas. The key to implementation of all of these recommendations is the length and
configuration of the SR 24 Bridge. If the bridge remains at its current length, the ability to
modify the levee system upstream is eliminated, and the processes of aggradation, increases in
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
levee and gravel ponds to allow flow to discharge through the gravel ponds and
back to the Yakima River. Reclamation could involve producing a hydraulic link
(groundwater or surface water) between the Yakima River and gravel ponds by
using interconnecting, backwater, and egress channels between adjacent pits to
increase flood storage capacity and enhance fisheries habitat.
• Obtain detailed topographic information and perform a hydraulic analysis to
determine allowable flows behind the levee. Design flows should be selected to
limit flooding impact on property near Riverside Road. If needed, a setback
levee could be integrated into the design to protect property near Riverside
Road.
• Promote open space land use between the Riverside Road and the Yakima River.
The Diking District is opposed to any modification of the levee or the land behind the levee
following the end of gravel extraction.
Based on the above analysis, and existing and planned projects in this reach, these flooding
issues and flood hazards are the highest ranking in the entire CFHMP planning area. Overall,
the river in this area should be managed to:
• Reduce the concentration of energy against the levees. This will reduce the current and
future rates of levee scour and failure.
o lower the bed elevation upstream and raise the bed elevation downstream.
o reduce the slope through the bridge location, reducing energy;
o reverse the aggradation process and increase the ability of the levee system
to control floods;
o lower the water table upstream of the bridge and raise the water table
downstream of the bridge.
• Increase the width of the floodplain to allow for a greater amount of sediment storage and
energy dissipation in the floodplain.
8-24
Design of this levee system should be done by the Corps of Engineers in cooperation with the
Yakima County Flood Control Zone District, Diking District #1, WSDOT, BOR, WDFW and the
Yakama Nation. Most of the property which would be subjected to increased flood frequency
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
erosive energy, water table rise, scour at and downstream of the bridge, etc, will continue into
the future.
SR 24 Bridge: The new bridge should be lengthened to approximately the location of the
existing intersection with Keys Road. This will allow reconfiguration of the levee system to
meet the above objectives. Currently this alternative is being considered by WSDOT and
funding is available for this option.
Levees Upstream of SR 24: The levees should be reconfigured to tie into the SR 24 abutments.
On the east side of the river, levee setback would begin upstream of the Old Moxee Bridge and
continue to the SR 24 alignment, this includes the demolition of the Old Moxee Bridge
Abutment itself. This would require purchase of two residential parcels and the KOA
Campground. Funds are currently available to acquire these parcels, and negotiations are
underway between the BOR and the owners of the campground. Negotiations will begin soon
for the other two parcels. Funding and design for relocation of the levees themselves is
available from the Corps of Engineers through their 1135 (Environmental Restoration) program,
with a 25% match. The match for this section will likely be met by providing the materials in
the existing levee (which are owned by Yakima County) to the levee relocation project.
On the West side of the river there is little opportunity to realign the levee system due to
Buchanan Lake and the WWTP, both of which need to be protected at all costs into the future.
Removal of the western Old Moxee bridge abutment, and reworking of the lower 150 feet of the
levee in that area would provide significant benefit to sediment transport and river alignment
through this reach. Currently, the abutment is an overlook for the Greenway and also has a
vault toilet located there. These facilities could easily be replaced on the reconfigured levee.
Funding for these activities is also available from the Corps.
Levees Downstream of SR 24: Levee setback in this area should be designed comprehensively
and to meet Corps of Engineers and FEMA standard for protection from the 100 -year
floodplain. On the east side of the river, the levees should be set back to allow the
incorporation of the Newland Pits into the floodplain. For a distance of approximately 2300
feet south of SR 24, the levee should be located west of Blue Slough, since Blue Slough in this
area was constructed and functions as an irrigation ditch, and the response of Blue Slough to
flood events would be negative from both a habitat and flood hazard standpoint. Due to the
topography in that area, levee construction costs will be lowest directly adjacent to Blue Slough.
After approximately 2300 feet south of SR 24 (near the northern boundary of the Central Pre-
mix property proposed for the East Valley Mine) Blue Slough is a natural spring -fed channel
and incorporation into the floodplain would have large environmental benefits. The levee
could either extend downstream a similar distance as the current levee, or stop in the vicinity of
the lower boundary of the CMP property, to allow the wetlands and lower elevation property
in that area to be re -incorporated in to the floodplain. If the levee is shortened, small levees
could be constructed to protect several homes adjacent to the BOR's property.
8-25
On the west side of the river, the ability of the City of Yakima WWTP to continue to discharge
in conformance with state law must be maintained. Meeting this requirement will require a
study of alternatives for discharge which will include a re -analysis of the expected 10 year 7
day low flow (this flow has recently increased due to changed operation of the river by BOR,
which should actually make the discharge standards easier to achieve), and alternative outfall
locations or configuration, or changing the point of discharge to existing or constructed
wetlands adjacent to the WWTP. In any event, setback of the levees downstream of SR 24
should not occur until the WWTP's ability to continue to discharge is assured. Funding for this
action is not currently secured, and may be the most difficult to secure. Currently, the Flood
Control Zone District, the BOR, and Ecology are working cooperatively to secure funding for
this action. Incorporation of this action into the CFHMP as integral to reduction of flood
hazard in this reach is a crucial step in broadening the funding sources (to include flood hazard
reduction as well as fisheries restoration grants) which could be used to implement this action.
Effects of the action
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
from this alignment is already owned by BOR or other public entities, gravel pits, pasture, and
some properties with residences. These properties could either be purchased under existing
funding programs, or remain in use, although some residences would be subjected to fairly
extreme flood hazard. Funding for levee design and construction is also available from the
Corps of Engineers for this portion, but finding the 25% match may be difficult. The large
environmental (fish habitat) benefits of this proposal make the funding sources such as the
Bonneville Power Administration or the Salmon Recovery Funding Board appropriate sources
of match.
Obviously, the effects of relocation of the levee would be large, and would be examined in
detail by the Corps in their design process. Several things should be stressed at this point in
consideration of this recommendation. The models cited above regarding the extent of the
floodplain do not take the existing Diking Improvement District #1 levee into account, because
the levee does not meet Corps standard for a 100 -year levee. Conceptually, therefore, there is a
very large difference between the regulatory floodplain (which has direct relationship to land
use and building code regulations) and the actual area that is flooded during a 100 -year event.
See Figure A8-10 that shows the extent of the regulatory floodplain and the location of the
current Diking District #1 levee. While the Diking District #1 levee does not meet Corps
standards, it is a large and durable facility, and did not fail or overtop in the 1996 flood, which
peaked just above the modeled 100 -year flood. Practically, the area flooded in less than 100
year floods is all west of the levee, and the depth of water in the floodplain is much greater
than the floodplain models predict.
Therefore, the areas between the existing DID #1 levee and I-82 are actually much more prone
to flooding and damage than what is depicted on the floodplain maps. This includes the City
WWTP, and several areas along I-82, that although they are not mapped to show they will
overtop, will overtop during a 100 -year event. Conversely, the areas east of the levee are not
subjected to very high flood hazard, but are mapped as if they are. This has a big effect on the
suitability of the areas north of SR 24, which are currently zoned for Light Industry, for
industrial development. Or more simply, the current floodplain maps do not depict
accurately the current flood hazard or what actually happens during a flood.
8-26
Diking District #1 does support actions as outlined above.
A8-10: Regulatory Floodplain and DID #1 Levee downstream of SR 24
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Practically, setback of the levees south of SR 24 and building them to a 100 -year protection
standard will result in expansion of the floodplain, and actual lowering of flood elevations and
flood hazard to the WWTP and I-82. From a regulatory standpoint, the regulatory floodplain
will actually decrease in size, and the modeled flood elevations will increase. Once the
floodplains are remodeled after levee setback, we should be in a situation where the practical
effects of a flood in terms of elevations and hazard are shown on the floodplain maps, and
reflected inthe floodplain land use and building regulations.
Figure
8-27
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
MR2 -Yakima Beech Street Gravel Pit Levee (2), and
Original Priority: 2 of 39
Amendment Priority: 2 of 39
UR5 — East Selah Gravel Pit Levee (28)
Original Priority: 28 of 39
Amendment Priority: 28 of 39
Problem Definition
Gravel resources continue to be a concern within the study area. Two gravel pits were
specifically mentioned in the CFHMP planning process; however, this discussion could apply
to any surface mining operation within the Yakima Valley. There are currently four permitted
gravel pits in the study area, and one permit pending approval. Existing and proposed gravel
pits in the study area include the following:
• East Selah Pit
• Yakima Beech Street Pit
• Newland Pit
• Riverside Pit
• The proposed Len Sali Pit near Union Gap.
Many of these gravel extraction areas shown in Figure 8-4, are designated natural resource
lands under GMA (RCW 36.70A). This assures the conservation of natural resource lands while
minimizing potential conflicts between adjacent land uses.
Concerns with floodplain gravel mining include the following:
• Providing a long-term source of gravel
• Protection of gravel resources and extraction equipment from flood damage
• Potential for severe flood damage caused by a sudden channel avulsion
• Increased flooding downstream or adjacent to gravel operations
• Increased river bank and riverbed erosion
• Impacts to groundwater quality and fisheries resources
• Consistency with future land use plans
• Maintaining floodplain storage capacity
• Gravel pit reclamation.
The Yakima Beech Street pit is separated from the Yakima River by a riverbank levee. The
levee is part of the COE-authorized levee system and provides 100 -year flood protection.
Currently, gravel extraction has ceased at this location and reclamation is expected to be
completed by 1998. A levee breach or failure during a significant flood event could cause a
sudden and drastic channel migration, which could direct floodwaters into areas that
previously experienced minimal flooding. This could result in significant flood damage, and
8-28
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
could damage fish habitat. During the November 1990 and February 9, 1996, floods, County
crews observed levee erosion and were concerned about a levee failure or breach.
The East Selah gravel pit is located adjacent to I-82, south of Harrison Road. The pit was
protected by a riverbank levee along the west perimeter of the property prior to the February 9,
1996 flood. During that flood event, the levee failed and the river channel shifted through the
gravel pit. The gravel pit was inundated, channel degradation and aggregation occurred, and
part of southbound I-82 was lost to bank erosion just upstream of the pit. In addition, gravel pit
levees directed floodwaters toward the right riverbank, which overtopped and created an
additional flow path toward the Selah wastewater treatment plant and Elks Golf Course.
Following the February 1996 flood, gravel pit levees were rebuilt to pre -flood conditions.
Recent studies by Dr. Mark Lorang of sediment transport capacity and sediment availability
indicate that the levee adjacent to the Beech Street pit is subjected to extremely high levels of
erosive force. Across the river and upstream, the levee just downstream of the Terrace Heights
Bridge also is subject to high levels of erosive energy (see figure A8-11 and also A8-7). Both of
these areas were the focus of emergency levee protection (i.e. end dumping rock armor onto the
levee face) during the 1996 flood. In both locations energy was high enough to move the large
riprap in the levee and being dumped during the event. After the flood, both areas were
significantly armored.
8-29
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Areas of major
erosion in 1996
Figure A8-11 Location of levee erosion below Terrace Heights Bridge and near the
Beech Street Pit.
According to estimates of gravel transport in the Gap -to -Gap Reach prepared by Dr. Lorang, if
the levee fails, it would take several centuries to refill the Beech Street pit with natural supply.
Even if the river could be separated from the Beech Street Pit after a flood event (which would
undoubtedly be extremely expensive) the change to sediment transport while the pit was
connected to the river would dramatically increase the potential for failure of levees, bridges,
and other infrastructure downstream of the pit breach. Prevention of a breach of this pit should
be a high priority of the CFHMP. It is of special concern however, that high energy at this site
may prevent the reinforcement of the levee face, based on the 1996 flood experience. Because
the levee is located adjacent to the pit, if the face cannot be reinforced, the levee cannot be
reinforced in the rear, as was done in 1996.
Discussion of Alternatives
Gravel mining is and will continue to be an essential activity in the Yakima Valley. However,
gravel mining does have an impact on flooding conditions and environmental resources. One
of the goals of this CFHMP is to maintain the varied uses of existing floodplains while
integrating flood management measures that preserve or enhance other beneficial uses.
Therefore, the CFHMP process should prevent or mitigate increased flood hazards or
8-30
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
environmental impact that might result from future gravel mining while still allowing mining
to occur.
To address concerns associated with gravel mining, the following alternatives were evaluated:
• Construct spur dikes or overtopping levees near gravel operations to address
immediate erosion and flooding problems.
• Develop a surface mining advisory committee to work with gravel operators in
developing reclamation plans that fulfill the objectives of this CFHMP, future
land use plans, and other local river management plans and regulations (e.g., the
Greenway Master Plan).
• Conduct a study of the river's hydraulics, hydrogeology, and geomorphology to
determine the relationship between gravel removal quantities and the potential
for increased flood protection benefits. Documenting increased flood protection
by gravel mining could decrease gravel royalty rates. In addition, the study
would determine proper gravel pit location, design, and operation to limit the
potential for adverse impacts on groundwater, fisheries, and the natural
ecological and hydraulic functions of the Yakima River. The study could result
in a long-term gravel management plan for the County.
• No action.
If no action is taken the potential for loss of gravel production, channel avulsion, bank and
channel erosion, increased flooding near or downstream of gravel operations, loss of fish
habitat, and elimination of floodplain storage will remain. Alternatives that enhance flood
control, reduce environmental impacts, and provide economical gravel extraction include the
following:
• Siting gravel pits in areas of minimal channel migration or areas of future
compatible land uses
• Using structural measures such as spur dikes or overtopping levees
• Using interconnecting, backwater, and egress channels between abandoned pits
to convey floodwaters, add flood storage capacity and enhance fisheries.
• Stockpiling and processing extracted gravel off site in a low flood hazard areas
• Limiting gravel removal to average annual bedload recruitment.
Private operators, who carry out the majority of gravel removal in Yakima County, are
generally responsible for obtaining required permits, excavating and processing the material,
finding purchasers, and transporting the material to the purchaser. Operators are required to
obtain lease agreements and report regularly to the Washington State Department of Natural
Resources (DNR) on the volume of gravel they remove. DNR regulates surface mining under
RCW 78.44. In addition, gravel operators must follow regulatory requirements outlined in the
Washington State Hydraulic Code (WAC 220-110-010), Shoreline Management Program (WAC
173-19-470), State Environmental Policy Act (RCW 43.21), Washington State Growth
Management Act (RCW 36.70A), and local Flood Hazard and Critical Areas Ordinances.
8-31
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
As numerous regulations govern gravel mining, it is necessary to work closely with gravel
operators to develop an approach that is consistent with economic, regulatory, and CFHMP
goals. Gravel operators are interested in a profitable operation; state agencies are concerned
with limiting environmental impact; citizens are concerned with limiting flood potential; local
agencies are concerned with compatible land use; and gravel consumers are interested in
maintaining a reliable source of building materials. Incorporating these varied interests is
critical to the success of providing a reliable source of gravel while maintaining the natural
function of the Yakima River floodplain.
Preferred Alternative
To address immediate and future flooding issues, both short-term and long-term alternatives
are proposed. Short-term recommendations address erosion and flooding issues while long-
term recommendations address many of the issues voiced by a variety of affected parties.
Short-term
Spur dikes and additional bank protection are recommended along the Beech Street levee to
reduce levee erosion. Spur dikes recently installed at the East Selah Gravel Pit should be
monitored during flood events to ensure that they are protecting I-82 and the East Selah pit
levee.
Actions at this location should be designed to reduce the overall amount of energy exerted
against the levee, and therefore the potential for levee erosion, at this location and across the
river upstream where conditions are similar. Actions should also seek to not increase or
reduce energy downstream, which is also experiencing erosion at the toe of the levee.
Installation of spur dikes at this location could reduce flood hazard here, but would increase
the danger of levee erosion downstream, while further decreasing conveyance capacity in a
relatively narrow reach which is currently aggrading and will continue to do so in the future.
Energy available for erosion of levees can be reduced in several ways - by restoring sediment
transport (the energy is expended on natural river processes instead of against the levees), by
decreasing the depth and concentration of flow (by widening the channel or reducing the rates
of aggradation).
At this location, the opportunity exists for widening of the channel and improving (for
sediment transport) the configuration levee system by setting back the levee opposite from the
Beech Street Pit, and this action should be taken. This levee setback would impact areas
currently managed as pasture, and could be a portion of the larger levee reconfiguration above.
The previously recommended actions of levee reconfiguration upstream of SR 24 will benefit
this area as well by improving sediment transport through this reach. Setting back the levee in
this action will also increase the benefits derived from actions below by increasing natural
riverine functions such as allowing the river to meander and re -grade the floodplain between
the levees to a lower elevation. Additional armoring of both locations with spur dikes should
occur in conjunction with levee realignment.
Long-term
Due to the location of the East Selah gravel pit, large flood events will continue to affect the
property in this area. Following gravel extraction, long-term modifications should include a
8-32
The Yakima County Planning Department has taken the lead, in cooperation with DNR,
WDFW, the Yakama Nation, and other parties in addressing the effects of gravel mining on the
river, including abandoned/played out pits, existing operations, and recommendations for the
siting and operation of new gravel mining operations. The study includes studying the
biological, hydrologic, and sediment transport effect of gravel pits, as well options and
recommendations for re -connection or restoration of certain types of pits, as well as those areas
which not be restored or reconnected to the Yakima River or its floodplain.
In addition, over the long term (i.e. in approximately 15-20 years or sooner if possible) the
existing Terrace Heights Bridge should be modified to improve sediment transport and reduce
the concentration of energy downstream. The current configuration of the piers and wingwalls
of the bridge make the bridge very inefficient at sediment transport and "fix" the river in place
upstream and downstream of the bridge. Given the location of the bridge in the valley, and
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
levee designed to overtop during large flows. The existing levee constricts the floodway and
directs waters to the opposite bank. Long-term gravel pit restoration should enhance some of
the floodway function. An overflow channel should be constructed within the gravel
excavation area to provide conveyance of flood waters; this would increase floodway
conveyance capacity and floodplain storage, reduce flood water elevations on the west bank,
enhance fish habitat, and limit the potential for a sudden channel avulsion.
To provide a reliable source of gravel while maintaining the natural function of the Yakima
River floodplain, it is recommended that DNR act as a lead agency with support from the
County to develop a workable gravel management plan. Gravel reclamation plans should be
distributed to local agencies and interested parties. Comments on proposed plans should be
discussed and issues resolved. If there is sufficient interest, a surface mining advisory
committee could be formed. RCW 36.70A.020 codifies the goal of encouraging the involvement
of citizens in planning processes and coordinating between communities and jurisdictions to
reconcile conflicts. The surface mining advisory committee could be an efficient way to address
this planning issue. The committee is not required to do so, but would provide a means of
obtaining public acceptance and interjurisdictional coordination in developing countywide
gravel management goals and policies. If additional information is required, the committee
should recommend additional studies to determine flood protection benefits associated with
gravel extraction. The goal of the committee should be to produce a long-term gravel
management plan.
The plan should be developed with the understanding that reclamation is not a static process.
Rivers are dynamic systems; therefore, gravel management plans need to account for the
possibility of river channel changes. Given the nature of the Yakima River, it is likely that the
river will eventually recapture abandoned gravel pits. Policies should be developed to address
how areas of rapid channel migration will be redeveloped or protected if the river begins to
migrate into those areas. Gravel management plans need to be flexible enough to respond to
changing river conditions.
Long-term gravel planning and reclamation should allow the Yakima River to recapture the
floodplain following gravel extraction. This could be done by constructing interconnection,
backwater, and egress channels to increase floodwater conveyance capacity, reduce floodwater
elevations, enhance fish habitat, and limit the potential for sudden channel avulsions.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
conditions upstream, the bridge should not have to be widened greatly, if at all, but the
conveyance capacity needs to be dramatically improved. In the shorter term, the Flood Control
Zone District should examine the possibility of altering the upstream alignment of the
levee/Greenway trail system to improve conveyance through this structure.
LR7 - Capture of Edler Ponds (New Issue, 4)
Problem Definition
The "Edler Ponds" are a series of 4 mined gravel pits that are located on the Edler property,
which is east of the Valley Mall Boulevard exit on I-82. The pits parallel the river for a
distance of approximately 2500 feet, and are generally 25-30 feet deep and 500 feet wide, and
the ponds are separated from each other by 100 feet +/-. In 2002, the most downstream of
these pits was connected to the Yakima River during normal flows. In the flood event of
February 2003 (approximately 22,400 cfs at peak) the river partially moved into the pit, and
probably as a result of loss of bedload to the pit, portions of the floodplain downstream were
converted to channel, and existing channels downstream deepened. Generally, the river and
new channels were moving closer to I-82, or adjacent to I-82 in the vicinity of the Spring Creek
gate under I-82. In addition, there is a portion of the old Diking Improvement District #2
levee, which was abandoned in 1968, just downstream and riverward from the pit that has been
captured.
In general, the situation is similar to the situation that occurred in 1972 when the river avulsed
from its former channel on the east side of the valley, to its current location along I-82. This
situation is aggravated by the existing abandoned levee, as this levee could force the river
against I-82. As occurred in 1972, there is the potential for significant erosion of I-82 in the
short term should avulsion occur. Also, as currently exists for the area where the Yakima River
is directly adjacent to I-82, fish habitat would be extremely poor in this reach if the riparian
zone were eliminated and the west bank of the river converted to riprap.
If the river does avulse toward I-82, there is a high probability that the Spring Creek Gate will
be closed permanently, as the volume of water in the river (even under normal flows) would
cause significant flood damage in the City of Union Gap to the east of the I-82.
Discussion of Alternatives
Capturing of the pit - At least partially the course of the river in this location is determined by
the configuration of the DID #1 levee, which forces the river to the west at this location.
Relocation of that levee as called for above, will reduce the potential for damage to I-82 at this
location. Another alternative is to build a new levee or lengthen the existing DID #2 levee in an
upstream direction to prevent capture of the pit by the river. The practicality of such an action
may be low due to the elevation of the bed of the river at this location (i.e. very downcut inside
the pit itself).
Protection of I-82 - near to and for 700 feet downstream of the Spring Creek Gate, I-82 is
currently unarmored. Below that point there are 4 large barbs in the floodplain that are
keeping the river from running directly adjacent to I-82, downstream of the barbs, the river is
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
directly adjacent to I-82. Installing additional groins in the small area of floodplain which
remains next to I-82 should be possible with a minimum of permitting difficulty.
Spring Creek Gate- During the February 2003 flood, there was significant flow from upstream
of the gate and all along I-82. After the flood, there was significant flow against I-82 down to
approximately 8000 CFS, which is well below what is considered a "flood" stage. There is a
good probability that the gate will have to remain closed for the foreseeable future.
Landowners who have water rights on Spring Creek are affected by this closure, but flow in
Spring Creek remains fairly strong even with the gate shut due to the creeks elevation relative
to the river as discussed in the previous flooding issue. Closing the gate may have some
negative effect on fish habitat and migration by eliminating the potential for restoration of
Spring Creek, as a side channel of the Yakima River.
Of possibly greater concern, the gate is currently not armored, nor does it appear to be
constructed to withstand significant flow velocities. The gate should be armored or reinforced
to prevent erosion or failure of the gate during a flood event.
Preferred alternative
The WSDOT should construct barbs similar to the existing downstream barbs to protect I-82.
The Spring Creek Gate should be reinforced to prevent failure during a flood event or avulsion
caused by pit capture. A new channel for Spring Creek (approx 550 feet long) should be
constructed outside the I-82 clear zone, and fish habitat elements installed in this new channel.
MR5—Development near Hartford Road (5), and
Unchanged/Unresolved
UR2—Development of Pomona, East Selah, and Selah Areas (6), and
LR4—Development near Riverside Road (22)
Resolved in Plan 2015
Problem Definition
Development continues in the Yakima River floodplain. Concerns have been voiced regarding
continued development near Hartford Road; in the Pomona, East Selah, and Selah areas; and
near Riverside Road. If development continues based on existing zoning and proposed land
uses under Plan 2015, the potential for flood damage will increase. Concerns over future
development in these areas are addressed here and in issue RW11 —Consistent Land Use and
Zoning. Concerns over floodplain structures are addressed in issue RW17—Existing Structures
in the Floodplain.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Discussion of Alternatives
Near Hartford Road, underlying zoning is Suburban Residential (SR), and the area is within
both the Floodplain Overlay Zone (FOZ) and the Yakima Urban Area (YUA). The Yakima
Urban Area Zoning Code requires allowable uses in this zone to undergo a Class 2
discretionary review due to the FOZ designation. A Class 2 review requires notification of
adjacent property owners and the presentation of a site plan to the Planning Department. A
Class 2 review gives the County more discretionary power in determining if the proposed use
is consistent with anticipated flood hazards than does a Class 1 (permitted use building permit)
review. The net effect of a Class 2 review is more scrutiny and public awareness of potential
large-scale developments in the floodplain.
Land uses most directly affected by this provision are single -wide or double -wide
manufactured homes. These uses, permitted in the underlying SR zone, are not exempt from
increased review requirements of the FOZ. All other land uses are either categorically exempt
(single-family detached residences, agricultural buildings or duplexes) or already subject to a
more stringent Class 2 or Class 3 review (all other land uses).
Developments that are categorically exempt must still meet the location and floodproofing
requirements of the NFIP, as outlined in Chapter 5 of the CAO, but are not likely to be
prohibited from the 100 -year floodplain. Additionally, the SR zone contains a special caveat
that restricts development density to one unit or less per net residential acre in areas prone to
flooding.
According to these provisions, placement of SR zones in correlation to the floodplain becomes
critical. The zone's mix of allowable uses, levels of review, and special caveats required for
each use indicates it is somewhat compatible with flooding activity so long as the regulatory
floodplain is accurate (causing the FOZ to apply to areas of heavy flooding), and so long as the
CAO is upheld both in Class 2 review of development proposals and in building permits issued
for FOZ categorical exemptions.
The area near Hartford Road is within the City of Yakima's Urban Growth Area (UGA),
indicating that the City's land use plan contains recommendations for future development of
the area. Specific zoning requirements for this area will be developed by the City and County
following completion of their respective comprehensive plans, although drastic changes from
present zoning are not expected. If no action is taken, Suburban Residential zoning according
to the current definition will continue in the area, resulting in moderate -density development.
This issue remains largely as stated above; current zoning designation in this area is still SR.
In the areas of Pomona, East Selah, and Selah, existing zoning is primarily Exclusive
Agriculture (EA) or General Rural (GR). The area is not within the Yakima Urban Area,
indicating that the Yakima County Zoning Code has jurisdiction, and there is no FOZ
associated with the regulatory floodplain. The EA zone enforces a minimum lot size of 40 acres
and permits only agriculture -based land uses, one single-family dwelling or mobile home per
40 -acre parcel, and accessory structures required for the practice of agriculture. The GR zone
permits all uses within the EA zone, and also allows small-scale, low-density residential
development. Minimum lot size within a GR zone is 1/2 acre. Potential developments in this
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
area are subject to the County's standard review procedure, not the three-level review process
associated with urban area zoning.
Future proposed land use is either Urban or Rural Transitional. This suggests a gradual shift in
land use from agriculture to urban development. The areas designated Urban would transition
within the current 20 -year planning period. Residential development would be clustered in the
transitional area north of Selah. Specific zoning requirements for these areas will be developed
by the City of Selah and Yakima County following completion of their respective
comprehensive plans, but are not expected to differ substantially from current conditions with
the exception of the clustering requirements. Given these assumptions, significant flood effects
are not expected to increase from current conditions. If no action is taken, the area will
gradually transition from rural to clustered residential and transitional land uses.
Project -specific impact would be mitigated in these areas using elevation and floodproofing
requirements for development in the floodplain, as described in Selah's Flood Hazard
Ordinance and Yakima County's CAO.
Near Riverside Road, existing zoning is General Rural, allowing for the continued practice of
agriculture, but also allowing residential developments of up to 2 units per acre. Subdivision
allowances in this limited access area may increase the development density, and therefore
increase potential for flood damage. The area is not within the existing Yakima Urban Area;
thus, the Yakima County Zoning Code applies to the area, and no FOZ is associated with the
regulatory floodplain.
The area along Riverside Road near Birchfield Road and south of SR 24 is within the City of
Yakima's future UGA. The remaining section of the road to the south is within an area
proposed for self-sufficient land use. Specific zoning requirements for these areas will be
developed by the City of Yakima and Yakima County following completion of their respective
comprehensive plans, although no significant differences are anticipated since the goals of self-
sufficient land use are consistent with the purposes of the General Rural zone. If no action is
taken, General Rural zoning will remain in the area. One concern would be the zoning applied
to the north section of the road if it remains within the UGA and receives an urban zoning
designation other than Suburban Residential, which has been determined to be somewhat
consistent with flooding activity. Project -specific impact would be mitigated using elevation
and floodproofing requirements present in Chapter 5 of Yakima County's CAO.
Additional regulatory tools can further reduce future flood damage potential in the Hartford
Road, Pomona, East Selah, Selah, and Riverside Road areas. Regulatory control alternatives
that were considered include the following:
• For the entire floodplain, apply a flood hazard overlay zone (FOZ), similar to the
FOZ found in the Yakima Urban Area Zoning Code
• Revise the land use plan proposed in Plan 2015.
An FOZ reinforces flood hazard reduction requirements contained in Chapter 5 of Yakima
County's CAO, and increases the scrutiny and public awareness of major development
proposals in the floodplain. It adjusts procedure rather than regulation. No new regulatory
requirements beyond those of the NFIP and CAO are introduced. Expanding the FOZ to
contain the entire floodplain, whether or not the floodplain lies within the Yakima UGA, will
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
provide consistent scrutiny and public awareness of flood hazards throughout the Mid and
Upper Valleys.
The area near Hartford Road is within the Yakima Urban Area and is therefore subject to
regulations in the Yakima Urban Area Zoning Code, including the existing flood overlay zone.
Chapter 5 of Yakima County's CAO should continue to be enforced in this area.
Expanding the FOZ to include the Pomona, East Selah, Selah, and Riverside Road areas would
provide a means by which the County and City could review development proposals and
require appropriate and consistent mitigation strategies. Extending the FOZ to include these
areas implies an addition to the County's zoning code. An interlocal agreement between
jurisdictions or modifications to existing ordinances (see issue RW5 — Revision and Consistency
of Critical Areas Ordinances) would ensure that the same elevation, floodproofing and
development prohibition requirements would apply.
Near Riverside Road, the County may either adopt an FOZ as part of the County zoning code
or extend the Yakima Urban Area and UGA boundaries to include the Riverside Road area and
apply the existing FOZ from the Yakima Urban Area Zoning Code. In either case, the overlay
zone would extend the requirements of Chapter 5 of the County's CAO to new development
within the zone.
The area near Hartford Road, currently zoned Suburban Residential (SR), should not remain as
such. If 160 acres of SR zone within the floodplain near Hartford Road were allowed to
develop to build out at a maximum density of 1 unit per net residential acre, this would result
in an addition of approximately 30 dwelling units within the floodplain (Table 8-4).
Eventually, revision of the recommended land use plan and subsequent zoning should consider
removing urban designations from the Pomona, East Selah, and Selah areas. Transitional
designations should remain, but should require residential clustering and mitigation actions
consistent with the CAO. Modifying the recommended land use plan should precede plan
adoption. Following adoption, a comprehensive plan amendment would be required; this is
allowed no more than once a year under the Growth Management Act.
The primary effects of development near Riverside Road are expected to be long term. Adverse
effects are likely only if subdivisions permitted under existing regulations are approved in the
area. Such subdivisions are still subject to the minimum elevation and floodproofing
requirements of the NFIP, as expressed in Chapter 5 of the CAO. Future flood hazards in this
area could be effectively reduced by limiting excessive subdividing through a discretionary
building permit process associated with extension of an FOZ.
TABLE 8-4.
BUILD -OUT CALCULATION FOR HARTFORD ROAD
Condition
Operation Yield
Floodplain area within SR zone in area
bounded by I-82, Terrace Heights Dr.
and Butterfield Rd.
Area measurement
160 acres gross
developable area
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Deduction for rights-of-way and 40% gross area deduction (56 acres)
Critical Areas
• 25% Right -of -Way
• 15% Critical Area
Deduction for existing parcels in open Deduct 36 net acres
space tax status
Deduction for existing residential Deduct 36 net acres
structures (Assuming conforming uses
and SF detached homes, 36 structures
at 1 unit per net residential acre)
Additional residential capacity
104 acres net
developable area
68 acres net
developable area
32 acres net
developable area
Round to nearest 10 30 additional units
One unit . er acre . er SR zone in flood .lain
The areas of Pomona, East Selah, Selah, and Riverside Road referred to above have either
remained in a land use zoning category which would allow a similar density (i.e. zone changed
from Exclusive Agriculture to Agriculture) where existing density was already low, or lowered
further (from General Rural to Remote/Extremely limited) where existing density was
moderate. The above discussion regarding these areas is now moot.
Preferred Alternative
Implementation of flood hazard overlay zoning should be sufficient to mitigate short-term
flood hazard impact of development near Hartford Road, Pomona, East Selah, Selah, and
Riverside Road. Actions necessary to implement the FOZ alternative include the following:
• Enforce the requirements of Chapter 5 of the CAO to any future development in
the Hartford Road area, either as part of a Class 2 review necessitated by the
FOZ, or as a condition for approval of FOZ categorical exemptions.
• Expand the FOZ to include the entire floodplain. This designation should be
similar to the FOZ found in the Yakima Urban Area Zoning Code. It should
reinforce requirements for new development to be constructed to NFIP
standards identified in the CAO. Site -planning and adjacent property
notification procedures in the UA Zoning should be extended throughout the
floodplain to heighten public awareness and increase scrutiny of development.
• Develop consistent ordinance requirements in the FOZ for all jurisdictions (see
issue RW5 — Revision and Consistency of Critical Areas Ordinances).
The County should also revise the recommended land use plan, as well as its policy on
permitted subdivisions within an FOZ. Actions necessary to implement long-term land use
changes include the following:
• Monitor cumulative effects of subdivisions in FOZs. If warranted, develop
review procedures to reduce cumulative effects of such development and amend
the procedures to the existing subdivision ordinance.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Revise land use plan by removing urban zoning designations from the
floodplain near Hartford Road, Pomona, East Selah, and Selah areas or limit
development density through Class 2 review process.
• Revise land use plan by removing urban designations within the floodplain from
Hartford Road, Pomona, East Selah, and Selah areas or require residential
clustering and mitigation actions consistent with the CAO.
• Monitor land use changes following adoption of the GMA comprehensive plan.
Ensure that future plan amendments are consistent with overall CFHMP goals
and policies, as well as recommendations pertaining to these specific locations.
• As part of future comprehensive plan amendments, consider adopting the
CFHMP as a comprehensive plan element. GMA requirements for internal
consistency will then apply to land use recommendations across both
documents.
Given that these recommendations have largely been followed in the update of the
Comprehensive Plan, much of the above is moot with the exception of the Hartford
Road Area. This area should be focused on in the next update of Plan 2015.
RW1— Floodplain Mapping (4); and
MR1— Gordon Lake Levee (17)
Problem Definition
The extent of the 100 -year floodplain boundaries has been debated since FEMA issued the
initial floodplain maps in 1985. The accuracy and methods used to determine the floodplain
boundaries have been questioned. Floodplain residents say the maps are frequently inaccurate
or do not reflect existing conditions and historical flooding information. Specifically,
floodplain boundaries are questioned downstream of Gordon Lake in the City of Yakima, in
East Selah, and below the SR 24 bridge.
Discussion of Alternatives
FEMA maps are currently being updated to reflect a revised Yakima River Flood Insurance
Study (FIS) performed in 1994. The Geographical Information System (GIS) representation of
the revised preliminary FEMA floodplain maps is included in Appendix A. Final revised
FEMA floodplain maps have yet to be adopted. The preliminary maps were issued December
7, 1995, and incorporate the following changes in hydrologic and hydraulic conditions:
• Revised hydrologic analysis to determine flood flows
• Installation of flood -control structures on Spring Creek. These include a flood
gate installed north of Valley Mall Boulevard and diversion of Spring Creek flow
to Wide Hollow Creek near its outlet by plugging Spring Creek's outlet culvert
• Incorporation of I-82 as a barrier to prevent floodwater from spreading to the
west along the river reach between Selah Gap and the Burlington Northern
Railroad bridge
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
• Raising and repairing the east bank levees upstream from West Birchfield Road
to Terrace Heights Boulevard to provide 100 -year level of protection
• Incorporation of COE-certified, 100 -year KOA levee.
Many of the concerns over past floodplain boundaries have been addressed by incorporating
the above changes. However, floodplain boundaries are still questioned in three areas:
downstream of Gordon Lake in the City of Yakima, in East Selah east of 1-82, and below the
SR 24 bridge. To assess the accuracy of predicted floodplain boundaries, historical information
was examined, especially the extent of inundation and flowpaths associated with the February
9, 1996 flood. This flood provided significant information on how a 100 -year event would
affect the study area. During this event, the peak flow was estimated at 57,500 cfs at the Parker
gauge, near the predicted 100 -year flood flow of 56,300 cfs. Table 8-5 compares high water
elevations collected by the County following the February 9, 1996, flood to those predicted by
FEMA for the 100 -year flood event. Locations of the high water elevations are displayed in
Appendix A. The largest discrepancies between the February 1996 flood and the predicted
elevations by FEMA occur at river mile 114.55, 112.52, 110.7, and 107.27.
TABLE 8-5
YAKIMA RIVER WATER SURFACE ELEVATIONS
Cross-section
Location February 9, 1996 Flooda Predicted Base
(river mile) Location Description (Flow=58,150 cfs)c Floodh
(Flow=56,300 cfs) c
117.20 Left side of Harlan Landing access road 1085.4 1084.7
115.78 Upstream end of R Street parking area 1066.5 1065.8
114.55 Left river bank P., 900 feet downstream of 1050.2 1043.8
Burlington Northern Railroad bridge
113.27 Terrace Heights bridge 1030.8 1030.7
112.52 Left bank levee 1,000 feet upstream of 1011.4 1013.7
Blue Slough closure structure
111.58 KOA campground levee downstream of 1005.4 1005.5
power pole
110.07 Left bank levee 74 3,000 feet downstream 995.8 994.0
of SR 24 bridge
109.46 Spring Creek flood gate 974.4 974.3
107.27 Union Gap upstream of SR 12 bridge 953.84 951.7"
(USGS gauging station)
a. SOURCE: 1996 County Field Survey
a. SOURCE: 1995 Revised Preliminary FEMA Flood Insurance Study
a. Peak flow at Parker gauge as reported by the Bureau of Reclamation.
a. SOURCE: USGS gauging station near Union Gap.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Downstream of Gordon Lake in the City of Yakima
The Gordon Lake levee extends along the right bank of the Naches River between I-82 and the
Burlington Northern Railroad grade near the confluence of the Naches and Yakima Rivers. The
revised Flood Insurance Study (FEMA 1995) identified elevations at the levee's east end to be
below freeboard standards. As a result, the 100 -year floodplain boundary extends downstream
of Gordon Lake, across North First Street, and downstream along the west side of I-82. The
levee contains floods up to and including the 100 -year event, but has less than 3 feet of
freeboard for events greater than the 50 -year (FEMA 1995). Since levee elevations are below
FEMA standards, floodplain boundaries in this area were determined as if this levee did not
exist and weir flow would occur through the underpass of SR 12.
The existing levee elevations range from over 5 feet above the BFE to 1.2 feet above the BFE. To
bring the levee up to FEMA freeboard standards, approximately 1,000 feet of levee would need
to be raised. The raised levee section would begin approximately 500 feet northeast of the
Burlington Northern railroad grade and extend to I-82. Approximately 7,000 cubic yards of fill
material would be needed.
Raising the levee would have minimal environmental impact and allow removal of a portion of
the regulatory floodplain. This reflects existing conditions, since historical flooding has
produced minimal flood damage downstream of Gordon Lake. During the February 9, 1996,
flood, floodwaters were estimated to be 2.0 feet below the top of the levee at its lowest elevation
and no damage occurred on or downstream of the levee. If no action is taken, future
development below Gordon Lake will continue to incur costs associated with floodproofing
and elevation requirements even though a significant flood hazard does not exist.
East Selah
In this area, floodwaters are predicted to overtop I-82 south of the Harrison Road interchange
and extend toward East Selah Road. Based on this prediction, a large portion of East Selah
would be inundated. However, this did not occur during the February 9, 1996, flood event.
I-82 actually acted as a barrier to limit the spreading of floodwater into East Selah. The river
eroded portions of the I-82 embankment downstream of the Harrison Road interchange, but
did not overtop the freeway. Floodwaters entering East Selah appeared to be a result of a
drainage canal east of I-82 that is linked to the Yakima River. The limited conveyance capacity
of this drainage channel resulted in some flooding, but not as severe as was predicted in the
preliminary floodplain maps.
Below SR 24 Bridge
Floodplain boundaries below the SR 24 Bridge are predicted to extend east toward Riverside
and West Birchfield Roads. A 25 -year levee currently exists on the east riverbank. In
determining floodplain boundaries, FEMA represented the river hydraulics as if the levee did
not exist, as it did not meet FEMA's freeboard standards. As discussed in issue LR5 —
Additional Flood Protection Below SR 24 Bridge, floodplain boundaries are overestimated since
the levee was disregarded in the FEMA hydraulic analysis. If the 25 -year levee was
represented in the hydraulic analysis, it is predicted that flood boundaries would not extend as
far to the east as shown by FEMA. In addition, in the event of February 9, 1996, floodwaters
were contained within the existing 25 -year levee.
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Much of the above has been resolved:
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Preferred Alternative
If no action is taken, the 1985 floodplain maps with their inaccuracies will continue to be used
to enforce floodplain ordinances. Building standards, such as floodproofing and elevation
requirements, will be applied to areas recently removed from the floodplain.
To correct for the inaccuracy of past floodplain boundaries, the County and other local
jurisdictions should adopt the preliminary revised floodplain maps on an interim basis. The
maps should be used to enforce floodplain hazard ordinances for new development. Adopting
the revised maps would eliminate many of the inaccuracies displayed in the 1985 maps.
While using the revised preliminary 1995 maps on an interim basis, the County should compile
data for other areas of floodplain inaccuracies. The data should incorporate information
collected from the February 9, 1996 flood. Actions should include the following:
• Obtain additional high water elevations throughout the floodplain resulting
from the February 9, 1996, flood. High water elevations should be taken at
FEMA -defined cross-sections or at COE high water elevation points. The COE is
currently collecting numerous high water elevations. The survey data should be
finalized by August 1996 (Weber, J., 19 June 1996, personal communication).
This information should be used to verify the hydraulic model used to define
regulatory floodplain boundaries and enforce the floodplain ordinances on an
interim basis.
• Obtain accurate topographic data throughout the floodplain specifically for the
Gordon Lake levee, left bank levee and floodplain downstream of the SR 24
bridge, I-82, and the floodplain near East Selah.
• Raise the Gordon Lake levee to FEMA freeboard standards.
• Base floodproofing and elevation building standards on February 9, 1996, high
water data since it is the best available data and the flows approximated the
predicted 100 -year event.
• Submit certification forms and supporting data to FEMA to obtain a Map
Revision following FEMA guidelines (FEMA 1990).
• Request that FEMA produce a digital floodplain map that combines all
jurisdictions and reflects recent data for use in the County's GIS.
The Gordon Lake Levee was raised by the City of Yakima, certified the Corps and is
reflected in the new floodplain maps.
The East Selah area should remain within the regulatory floodplain until that reach
stabilizes from the effects of the 1996 flood and levee breach into the East Selah pit. The
breach caused severe downcutting of the channel, which lowered flood elevations
during the flood. Since the repair of the levee, this area has been rapidly aggrading.
Efforts taken to remap this area would probably quickly be out of date due to the
rapidly changing conditions.
8-43
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Serious concerns regarding the mapping below SR 24 remain. See discussion at the end
of LR5 above.
RW13—Funding for Flood Control Work and Restoration Projects (7)
Problem Definition
No secure funding has been allocated to the County's Public Works Department for flood
hazard management. Currently, the Public Works Department budgets $30,000 per year for
maintenance of flood facilities and $30,000 for emergency repair of flood facilities. Specific
funding is not available for designing and implementing flood management projects or
programs. The County has historically relied on federal and state disaster funding or on its
local road budget to repair damage associated with floods. These expenditures will continue to
occur unless funding becomes available to alleviate flood problems.
Chapter 9 of the CFHMP describes funding requirements, examines available funding options,
and suggests a preferred funding alternative based on preliminary estimates of the cost to
implement the CFHMP.
See introduction.and purpose and need.
RW11— Inconsistent Land Use and Zoning in the Floodplain (8)
Not Applicable, problems described in this section largely solved by Plan 2015 and the zoning
designations therein.
Problem Definition
Flooding does not become a problem until land susceptible to flooding is developed for uses
not compatible with flooding. It is essential that jurisdictions establish land use plans that
recognize this potential and implement those plans through zoning regulations that clearly
identify allowable densities and mitigation requirements.
Yakima County is authorized to prepare a CFHMP under SB 5411. In addition, the GMA
requires communities to prepare comprehensive plans, including a land use element that
specifies how future development will be accommodated. When the plan is complete, the
County must prepare development regulations consistent with the plan. Yakima County is
responding to these requirements by preparing Plan 2015, scheduled for completion in 1996.
Plan 2015 and the CFHMP should be consistent with and complementary to each other. The
County's goal is to reduce the exposure of public and private property to flood hazards and
potentially to enhance public revenues available to complete projects identified in each plan.
Discussion of Alternatives
The issue of maintaining consistent land use and zoning in the floodplain was raised by
Advisory Committee members, and can be addressed as three significant subissues.
8-44
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Existing Land Use Incompatibility
Development incompatible with routine flooding has been allowed in several locations within
the floodplain. Incompatible land uses in the floodplain include residential, commercial, and
industrial development. Open space areas and utility corridors are more compatible with
natural floodplain activity. The Yakima Urban Area Zoning Code and Yakima County Zoning
Code specify the density and intensity of development allowed. The Yakima County Critical
Areas Ordinance (CAO) specifies allowable encroachment conditions and structural mitigation
requirements for development in these areas.
Approximately 8 percent of the Yakima River floodplain is currently residential. These
106 parcels are located throughout the study area, with concentrations in East Selah, west of
Butterfield Road, and west of Birchfield Road. CAO regulations would require that
construction within these areas mitigate potential flood damage through a variety of methods
(see issues RW4 and RW5).
Trade and services combine for approximately 4 percent of current floodplain use. The
11 parcels in trade or services use are located throughout the study area, with concentrations
around the I-82 interchanges with Selah Road and SR 24. Current CAO regulations for
developments of this type in these areas are similar to those for residential development, except
that such development would not be allowed to contribute any increase in base flood elevation
as a result of its encroachment on the floodway.
Existing Zoning Incompatibility
In a few floodplain locations, existing zoning allows potential future development incompatible
with routine flooding. Much of the floodplain area consists of the Exclusive Agriculture (EA),
General Rural (GR), and Suburban Residential (SR) zoning categories; SR is the most
incompatible.
The EA zone is intended to preserve areas for agriculture and to permit only those new uses
that are compatible with agriculture. Minimum lot size within this zone is 40 acres. One
single-family dwelling or mobile home is permitted per 40 -acre parcel. Permitted uses include
agriculture, horticulture, floriculture, livestock, and general farming. Plants for canning or
packing are also permitted. Within the floodplain area, EA zones are found downstream of
SR 24, west of Birchfield Road.
The GR zone is designed to maintain the openness and rural character of areas of the County
where agricultural zoning is not desirable. Minimum lot size within this zone is one-half acre.
Rangelands, small-scale farms, and low-density commuter residential development
characterize these areas. Permitted uses are consistent with those allowed in EA zones.
Residential development is limited to one single-family unit or mobile home per parcel.
Accessory buildings associated with permitted uses are also allowed. Much of the upper and
lower reaches of the study area are designated GR, with significant areas west of Selah Road
East, and south and west of Birchfield Road.
The SR designation of the Yakima Urban Area Zoning Code addresses County land within
urban areas. SR zones are intended as transitional areas that allow a mix of uses, ranging from
agriculture to single-family residences. Uses permitted within this zone are subject to one of
8-45
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
three levels of review. A Class 1 review, conducted by the Building Department, is required for
uses such as agriculture and industry, detached single-family residences, and home
occupations. A Class 2 review, conducted by the Planning Department, is required for movie
theaters, auditoriums, equipment storage, attached single- and two-family residences, and
retirement homes. A Class 3 review, conducted through a hearing process, is required for more
controversial uses, including public residential developments, multi -family residences, mining,
public facilities, and outdoor recreation facilities. SR zones near the floodplain can be found
along the Keys Road corridor, near Butterfield Road, and downstream of the Naches-Yakima
confluence near the First Street Interchange.
The density and extent of development within the GR zone determines its compatibility with
flooding. The permitted uses in this category are nearly identical to those in the EA zone, with
the primary difference being the minimum lot size. The extent to which GR areas are built out
determines their compatibility with flooding.
The SR zone includes a variety of uses, some of which are consistent with seasonal flooding.
The discretionary review process required for obtaining permits in this zone should consider
the floodplain status of the parcel and apply the recommendations of the CAO accordingly.
Single-family residential development is a permitted use in this category and is categorically
excluded from the Class 2 review required by the presence of an FOZ. However, the SR zone
definition contains a special caveat restricting residential density to 1 unit per net residential
acre in areas of potential flooding. The existing process may be able to weed out large multi-
family developments and larger developments, such as theaters and auditoriums. Single-
family residential development is allowed in an SR zone in the floodplain at a reduced density
if it meets the elevation and floodproofing requirements of CAO Chapter 5.
Potential Future Land Use/Zoning Incompatibility
Future land use plan alternatives are being proposed in Yakima County as part of Plan 2015.
The GMA requires that new land use plans be consistent with County zoning. Thus, new
development regulations will implement the recommendations of the land use plan. The new
policy framework eliminates traditional discrepancies between land use and zoning, and
combines current planning and environmental review processes required under SEPA. It
provides a particularly valuable forum for consideration of flood hazards.
Some areas within the preferred use alternative allow for urban development in the floodplain,
usually within a city's Urban Growth Area (UGA). The plan also proposes transitional
developments, self-sufficient developments, and rural settlement areas in the unincorporated
County near and within the floodplain. Development recommendations within these areas are
still in the planning stages; analysis of specific permitted development types is premature.
Self-sufficient areas are characterized by low-density development that does not require public
water or sewer. Residential development is permitted in these areas, but is kept at a very low
density. Self-sufficient areas near the floodplain include much of the area downstream of
SR 24, as well as areas upstream of Pomona Road East.
Rural Transitional areas are experiencing a transition from rural to urban development
characterized by increasing density and potential future service from a municipal or privately
8-46
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
owned water system. Transitional areas may contain a variety of uses and a mix of urban and
rural densities; however, the goal for these areas is to encourage rural cluster development at
approximately 3 units per 4 acres. They are generally compatible with existing Rural
Residential and Suburban Residential zones. A substantial rural transitional area can be found
north of Selah's UGA. Portions of this area are within the Yakima River floodplain.
Agricultural Resource areas are consistent with lands currently designated either EA or GA.
Development regulations in these areas are not anticipated to change substantially as a result of
the new land use plan. Agricultural resource areas within the Yakima River floodplain are
located primarily downstream of SR 24, east of previously identified self-sufficient areas.
Urban areas can be divided into those located within city limits and those located within a
UGA. In either case, prevailing land uses in urban areas are determined by cities. Cities and
counties jointly determine land uses and service provision agreements in unincorporated
UGAs. Uses and densities in these areas vary, and can be expected to include residential,
commercial, and industrial development. Without a detailed examination of city land use
plans for these areas, any prediction of specific floodplain impacts is speculative. However, the
GMA implies that agricultural development is rural in character and should be located outside
a jurisdiction's UGA. Therefore, unless the floodplain area is designated as an open space in a
jurisdiction's land use element, it is reasonable to assume that an Urban designation within the
floodplain implies an incompatible use.
Areas subject to this condition include most of the Yakima River floodplain upstream of the
Naches-Yakima confluence, the majority of the floodplain between the First Street Interchange
and SR 24, and the west side of the floodplain between SR 24 and Union Gap. Examination of
existing open space parcels as an indication of future conditions shows that much of the area
upstream of the confluence currently has open space tax status. However, much of the area
designated urban downstream from that point does not currently have open space status.
Some of these properties are part of the Greenway Foundation's master plan, and should
therefore be considered as open space in future land use plans.
Preferred Alternative
If no action is taken, current zoning will continue in the area until replaced by development
regulations from Plan 2015. New regulations are not expected to differ substantially from those
currently in force. Suburban Residential zoning will continue to permit single-family
residential development in the floodplain, and portions of the floodplain will be designated
Rural Transitional and Urban. Actions recommended to mitigate the flood hazard impact of
inconsistent land use and zoning include the following:
• A County -wide FOZ, recommended previously in this Plan, would also serve to
bring more consistency and clarity to existing and future land use plans and
zoning regulations.
• County and City land use plans and development regulations should be revised
to ensure that urban areas within the floodplain are dedicated to long-term open
space or low-density development with structural mitigation.
8-47
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
As stated above, these issues are largely resolved. Not mentioned here is the Light
Industrial Zoning north of SR 24 and east of Keys Road, which is located in the
regulatory floodplain. Implementation of LR5 above would resolve this incapability by
reducing the regulatory floodplain.
RW6—Public Disclosure of Floodplain Status (9)
Problem Definition
Buyers are often unaware of the floodplain status and associated flood hazards of the land they
purchase. Construction on or purchase of property in a floodplain may result in human health
or property damage to the purchaser, as well as additional cost to taxpayers of the County.
Alternatives Analysis
RCW 64.06.020 (1994) requires sellers of real property in Washington State to disclose to buyers
if a property is within a designated floodplain or designated flood hazard zone (items 7(d) and
item 7(e) of the real property transfer disclosure statement). Disclosure is based on the seller's
actual knowledge of the property at the time the disclosure form is completed. Response
options for floodplain disclosure include "yes," "no," and "don't know." No further
explanation or documentation is required. However, the seller is advised to obtain and pay for
the services of a qualified specialist to determine the floodplain status of the property.
Many benefits may be accrued from encouraging and supporting floodplain disclosure. If the
County participates in determining floodplain status for floodplain residents, citizens will
become more aware of the magnitude of the flood threat and associated risks, will be more
active in reducing flood risks, and could receive lower flood insurance rates (see issue RW7—
Flood Insurance and Public Education). Currently, zoning regulations in the Yakima Urban
Area implicitly support property disclosure by triggering project reviews for new projects or
use changes within the established flood overlay zone. However, new developments outside
the existing flood overlay zone, or floodplain property transfers, may take place without proper
disclosure of floodplain status.
If no action is taken, floodplain notification will continue per RCW 64.06.020, supported
implicitly in the urban area by flood overlay zoning when a new project or modification is
proposed. No formal County actions would be taken to increase public awareness of floodplain
location, potential impacts, or insurance availability.
The opportunity exists to increase floodplain disclosure by using the County's GIS to publish
notifications of floodplain occupancy to each affected property owner. These notifications
could be accompanied by information on the NFIP. This action would reduce the incidence of
"don't know" disclosure statements, increase flood insurance coverage in the County, and
possibly decrease flood insurance rates. GIS information, already in the possession of the
County, would save taxpayers the fees commonly associated with professional floodplain
determination services.
8-48
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Preferred Alternative
The County would achieve flood hazard reduction benefits by participating in a public
disclosure of floodplain status program. Actions to implement such a program include the
following:
• Designate a FOZ for the entire floodplain as recommended in issue
UR2—Development of Pomona, East Selah, and Selah Areas. The FOZ
designation should encompass the entire 100 -year floodplain, and should be
similar to the overlay zone found in the Yakima Urban Area Zoning Code. The
FOZ will implicitly support property disclosure by triggering project reviews for
new projects or use changes within the established flood overlay zone.
• Perform standard public notification of the FOZ zoning change, but include
information about floodplain status, the NFIP, and RCW 64.06.020 in the mailing
to all floodplain residents. Refer property owners to qualified floodplain
determination specialists, or establish a program to provide such services using
the County's GIS.
• Require disclosure of floodplain status in the subdivision ordinance for all newly
created parcels.
Issues under the first bullet resolved by Plan 2015, the second remains as a
recommendation.
RW12—Protection of State and County Roads (10)
Problem Definition
Numerous County roads suffer damage during flood events; this damage accounts for a
significant portion of flood repair costs. State and federal roadways are also susceptible to
flood damage. Much of the damage is caused by bank erosion in drainage channels along
roadways, undercutting of channel banks adjacent to roadways, or by overtopping floodwater.
Drainage and river channels adjacent to roadways experience high velocity flow that
undermines and erodes roadbeds. Flood damage results in a substantial strain on the County's
road maintenance budget in addition to limiting transportation and emergency response routes
during significant flood events.
Discussion of Alternatives
Chapter 4 describes road damage within the County by historical floods. Most of the road
damage is outside the study area. Damaged roads within the CFHMP study area are listed in
Table 8-6, with a description of the type of damage and recommended corrective action.
Altematives examined to reduce future flood damage and increase available transportation
routes during flood events include the following:
• Installation of drainage structures
• Roadbed / bank protection
• Road elevation or relocation
• Drainage channel alignment control
8-49
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Road closure database
• Emergency routing plan
• No action.
In general, damaged roads within the study area are located near Selah and Union Gap. Roads
are damaged by the erosive forces of floodwaters; erosion is greatest within high -velocity
drainage and river channels. Much of the damage could be mitigated by providing additional
bank protection or by directing flood flows toward the main river channel.
Floodwaters also result in closure of numerous roads in the study area. Road closures limit
emergency access, strand county residents, isolate critical facilities such as hospitals and
schools, and increase the risk to motorists. Yakima County has a good working knowledge of
when roads should be closed, but has not formalized road closure and emergency routing
procedures.
Preferred Alternative
Recommended corrective actions for roads within the study area are listed in Table 8-6.
Additional actions to mitigate future road damage include the following:
• Formalize a county -wide road closure and emergency routing procedures to be
used during a flood event. This could result in an emergency response plan that
includes a database and maps displaying road closures and emergency routes at
various river stages and that documents past flood damage.
• Based on the county -wide road closure database, prioritize roads requiring flood
damage mitigation. Obtain engineering information to develop effective
mitigation alternatives similar to the information in Table 8-6. Implement
recommended road damage corrective actions in order of priority, based on
available funding. Road enhancements should focus on critical transportation
routes.
8-50
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Table 8-61 page
TABLE 8-6.
DAMAGED ROADS IN CFHMP STUDY AREA
Road Name
Type and Estimate of
Damage
Recommended Corrective Action
Rushmore Road
I-82 between mile
post 27 and 29
SR 823 near Yakima
Elks Golf Course
I-82 at Selah
interchange
SR 12 near 16th
Avenue
I-82 at Union Gap
interchange
Thorp Road
I-82 near South
Union Gap
Road closure from
overtopping floodwater
(minimal damage)
Washed out southbound
lanes, embankment and
shoulder damage, fencing
and guardrail damage
($300,000)
Erosion of embankment
slopes ($50,000)
Road closure from
overtopping floodwater,
minimal damage (estimate
not available)
Erosion of embankment
slopes ($80,000)
Road closure from
overtopping floodwater
(damage estimate not
available)
Road closure from
overtopping floodwater,
embankment damage
($5,000)
Northbound lanes washed
out and southbound lanes
embankment damage
($550,000)
No Action since flooding resulted in
minimal damage and Rushmore Road is
not a critical access route
Monitor performance of recently installed
spur dikes during future flood events
Install additional bank protection
integrating bioengineering techniques
Obtain detailed topographic data in this
area to define flowpaths and examine the
feasibility of raising the highway to direct
floodwaters toward the main channel
Install additional bank protection
integrating bioengineering techniques
Obtain detailed topographic data in this
area to define flowpaths and river
hydraulics to examine the feasibility of
raising the highway or railroad grades or
increasing the conveyance capacity of
Ahtanum Creek near the mouth to direct
floodwaters away from the freeway.
Install additional bank protection
integrating bioengineering techniques
Obtain detailed topographic data in this
area to define flowpaths and river
hydraulics to examine the feasibility of
redirecting flood flows from the east side
of the freeway near the I-82 bridge to the
main channel.
SOURCE: Washington Department of Transportation, Yakima County
8-51
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
The Flood Control Zone District is currently developing a Countywide Flood Response
Plan that will address the above topics. The plan should be available for review in
October of 2003.
8-52
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
RW3 — Channel Migration (11), and
LR2—Protection of Private Property below SR 24 (14), and
LR1 — Erosion of Agricultural Land (20), and
UR1 — Erosion of Agricultural Land (27)
Problem Definition
Rivers have a natural tendency to change alignment, which may result in damage to property.
The extent and frequency of river movement vary by river reach. The Yakima River has a
greater tendency to migrate at the following areas: downstream of Selah Gap to Marsh Road,
from Hartford Road to Terrace Heights Drive, from west Birchfield Road upstream to the
Central Premix gravel pit, and downstream of the SR 24 bridge, as described in Chapter 4.
Channel migration or sudden channel shifts present flood hazards because they can erode
property and flood control structures and divert floodwaters into areas that historically
experience minor flooding. During a large flood, floodwaters may cause levees to fail, directing
flow away from the main channel. The resulting new channel may be a significant distance
from the former main channel, isolating businesses, homes, or farmland, or eroding significant
portions of land.
Private land owners have voiced concerns about protection of land from erosion. Near Valley
Mall Boulevard for instance, old levees that washed out in previous floods have not been
replaced. This has resulted in increased erosion of private land. Downstream of Harrison Road
and SR 24 Bridge, the river continues to shift laterally, resulting in loss of agricultural land.
Discussion of Alternatives
To control bank erosion effectively, riverbank management must be compatible with the nature
of the river system and the composition of its banks. Before erosion control can be applied, it is
essential to understand the mechanism of erosion. Within the study area, a hydraulic mode of
bank erosion is most prevalent. When bank erosion occurs because water flowing in the
channel exerts pressure that exceeds the critical shear stress for soil erosion, the mode of failure
is hydraulic (Fischenich 1989). Hydraulic failure is generally associated with noncohesive
gravelly banks in a river such as the Yakima River, and is characterized by lack of vegetation
and high boundary velocities. Therefore, preferred alternatives to reduce erosion within the
study area should integrate techniques that increase riverbank vegetation and reduce riverbank
velocities.
Preferred Alternative
If no action is taken, erosion will continue on private property and along the County's flood
control facilities. Continued erosion could eventually increase risk of future flood damage in
areas historically experiencing limited damage. Alternatives to manage excessive erosion
include the following:
• As bank erosion areas are identified, the County should implement bank
protection projects following established guidelines (e.g., King County 1993),
modified for Yakima County.
8-54
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
• The County should provide guidance in designing private bank protection
projects. Residents should continue to fund and implement bank protection
projects for their property on an as -needed basis. During project review, the
County should prefer bioengineering methods to address the hydraulic nature of
bank erosion.
• Limit development in rapid channel migration areas by promoting the Open
Space Taxation Program in a public awareness campaign (see issue RW10 —
Acquisition / Preservation of Floodplain Open Space)
• Adopt and enforce design standards, such as onsite detention, to limit or
mitigate increased erosion potential resulting from new development.
These measures are currently being implemented by multiple parties including the
Yakima County Planning Department, the Surface Water Management Division of
Yakima County Public Works, North Yakima Conservations District etc. In addition,
many of the most erosion prone lands have already been purchased by BOR, the
Yakama Nation or others, therefore the risk to private property from erosion is currently
much less than when the plan was written.
RW9 — Diversity of Opinions Relating to River Management (12), and
RW8 — County Policy on Flood Hazard Management (21)
Problem Definition
There is a diversity of opinion within the County regarding management of the Yakima River
floodplain and its tributaries. Interested parties include state regulators, local officials, property
owners, private interest groups, recreational users, and Native American groups. Their
interests include floodplain development potential, protection of private property,
enhancement of fisheries habitat and water quality, preservation of aesthetic qualities, water
conservation, and open space preservation, among others. Prior to GMA and CFHMP
planning, there was no continuing forum for the various interested parties to discuss flood
hazard management issues nor were there specific goals and policies to direct flood hazard
planning decisions.
Discussion of Alternatives
If no action is taken, the potential for inconsistent management of the Yakima River corridor
will continue. As issues arise, single -interest groups tend to overshadow multiple public
interests. The County is in a position to continue the public planning process, given its current
investment in GMA and CFHMP development. Continued facilitation of the CFHMP planning
process will reinforce the importance of the Yakima River corridor as a public resource to the
community. The net effect will be increased public awareness of floodplain management issues
and consistent planning throughout the Yakima River corridor.
Development of flood hazard policies is underway in the County. The Flood Hazard
Ordinance states its goal as minimizing the impact of flooding on lives and public and private
property. The Natural Setting element of Plan 2015 includes draft stormwater and flood
hazards goals and polices. The CFHMP defines planning goals and objectives. Consistency
across all planning efforts is needed to ensure a common vision in river management.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Table 8-7 compares CFHMP goals and objectives to Plan 2015 draft goals and polices. Overall,
they are similar and complementary. The only inconsistency is the exclusion of a Plan 2015
draft policy from the goals and objectives of the CFHMP. The excluded policy states, "Yakima
County should conduct additional analysis and mapping of frequently flooded areas in cases
where the 100 -year floodplain maps prepared by FEMA do not adequately reflect the levels of
risk or the geographic extent of flood hazards." While this is not included in the CFHMP as a
policy, it is addressed as a flood management issue.
8-56
E I NM all r In N MN— NM W I MN r N— — 1—
TABLE 8-7.
COMPARISON OF PROPOSED CFHMP GOALS AND PLAN 2015 GOALS
Proposed CFHMP Goal
Proposed CFHMP Objective
Related Goal / Policy proposed in Plan 2015
Identify flood hazards,
propose alternatives, and
select appropriate flood
hazard management
measures.
Implement short-term
actions to help alleviate
current flooding problems.
Ensure that development
proposals are consistent
with goals and objectives of
the CFHMP.
Establish and adopt a
systematic and
comprehensive approach to
flood hazard management.
Prepare a comprehensive flood hazard management plan to address
flooding problems m study area:
• At a minimum, propose permanent management measures for
the principal flood problems
• Select flood hazard management measures based on the
following criteria:
— Severity of problem
- Effectiveness, with emphasis on solving regional problems
— Cost
- Public acceptance
— Impacts
• Prepare a Capital Improvement Program (CEP) from selected
alternatives
• Secure County and Ecology approval of the CFI -IMP.
Identify maintenance actions and other changes to existing City and
County programs that can be achieved with existing resources.
Communicate with private developers to convey the results of
interim CFHMP analyses affecting proposed development parcels.
Review development proposals to ensure consistency with flood
hazard management alternatives that are likely to be developed in the
CFHMP.
Pursue strategies for flood hazard management that balance
engineering, economic, environmental, and social factors in relation
to stated goals and objectives
Evaluate goals and objectives every five years to maintain consistency
with current policy.
Maintain consistency with Yakima County and local comprehensive
plans, the state Growth Management Act, and related policy plans
through measures including:
• Providing appropriate public services for new developments.
• Preserving natural drainage areas, especially known floodplains.
• Adopting development codes that reflect policies on flood
hazard management.
Coordinate flood hazard planning with all interested and affected
parties in both public and private sectors:
• Coordinate with the Yakama Indian Nation
• Cooperate with reclamation district, utilities, WSDOT, etc.
• Coordinate with cities to solve mutual flooding problems
• Establish an Advisory Committee while developing the CFHMP
• Provide public opportunity to comment on flood hazard
management decisions
Improve public understanding of flood hazard management through
public education.
Goal NS -SW 4
Prevent increased flooding
Policy NS-FLH 5.5
Support comprehensive flood control planning
Policy NS-FLH 5.2
Prevent the loss of life or property and minimize public and private costs
associated with repairing or preventing flood damages from development
in frequently flooded areas
Goal NS-FLH 5
Establish land use practices in flood hazard areas so that development does
not cause or exacerbate natural processes which endangers the lives,
property, and resources of the citizens of Yakima County.
Policy NS-FLH 5.7
Direct critical facility development away from areas subject to catastrophic,
life threatening flood hazards where the hazards cannot be mitigated.
Policy NS-FLH 5.5
Support comprehensive flood control planning
MN la rr OS M MN E— r r r— — MI r OM OM In INN
TABLE 8-7.
COMPARISON OF PROPOSED CFHMP GOALS AND PLAN 2015 GOALS
Proposed CFHMP Goal
Proposed CFHMP Objective Related Goal / Policy proposed in Plan 2015
TABLE 8-7 (continued).
COMPARISON OF PROPOSED CFHMP GOALS AND PLAN 2015 GOALS
Proposed CFI -IMP Goal
Proposed CFHMP Objective
Related Goal / Policy proposed in Plan 2015
Establish a stable,
adequate, and publicly
acceptable long-term
source of financing.
Prevent the loss of life,
creation of public health or
safety problems, or damage
of public and private
property.
Maintain the varied uses of
existing drainage pathways
and floodplains within the
County
Prevent the degradation of
surface and ground water
Minimize the expenditure
of public funds, including
funding of emergency
measures, through effective
flood hazard management.
Determine flood hazard management funding needs and alternatives
in the CFHMP (i.e., a Capital Improvement Plan).
Establish a funding mechanism to help implement the CFHMP.
Implement flood hazard management measures as approved in the
CFHMP.
Give preference to nonstructural measures such as regulations and
preservation of existing drainage corridors.
Preserve opportunities for floodplain uses that are compatible with
periodic flooding. Discourage land uses in the floodplain that are
incompatible with periodic flooding.
Adopt flood control measures that preserve or enhance existing
fishery, wildlife, and other natural uses of the riparian zone.
Ensure that changes in land use in natural drainage corridors protect
and restore the natural character wherever possible.
Minimize the impact of contaminants and sediment in stormwater
runoff on receiving waters (Yakima River) and groundwater aquifers.
Integrate water quality needs with flood control needs to provide
consistency in flood hazard management.
Develop structural and nonstructural measures to prevent or
minimize existing flood problems that are the responsibility of the
County.
Adopt regulations to prevent new development from causing flood
damage or from being susceptible to damage by floods.
Adopt a drainage design guidance manual that includes uniform
standards for design and construction of private facilities and
minimum criteria for new development to mitigate the impact of
development on water quality, flooding, and erosion.
Policy NS-FLH 5.5
Support comprehensive flood control planning
Goal NS-FLH 5
Establish land use practices in flood hazard areas so that development does
not cause or exacerbate natural processes which endanger the lives,
property, and resources of the citizens of Yakima County.
Goal NS-FLH 5
Establish land use practices in flood hazard areas so that development does
not cause or exacerbate natural processes which endanger the lives,
property, and resources of the citizens of Yakima County.
Policy NS-FLH 5.3
Yakima County should not authorize flood control measures which
obstruct fish passage or result in the net loss or damage of fish and wildlife
resources.
Policy NS FLH 5.4
Encourage and support the retention of natural open spaces or land uses
which maintain hydrologic functions and are at low risk to property
damage from floodwaters within frequently flooded areas.
Policy NS -SW 4.2
Maintain natural drainage courses.
Goal NS -SW 5
Improve water quality through improved stormwater management.
Policy NS -SW 5.2
Control stormwater in a manner that has positive or neutral impacts on the
quality of both surface and ground water, and does not sacrifice on for the
other.
Policy NS-FLH 5.2
Prevent the loss of life or property and minimize public and private costs
associated with repairing or preventing flood damages from development
in frequently flooded areas.
Policy NS-FLH 5.8
Where the effects of hazards can be mitigated, require appropriate
standards for site development and for the design of structures in areas
subject to flood hazards.
Policy NS -SW 5.1
Review the recommendations of the Yakima Urban Area Storm Water
Management Plan, and develop a realistic implementation schedule.
MN la rr OS M MN E— r r r— — MI r OM OM In INN
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Adopting the CFHMP as part of Plan 2015, or expanding the CFHMP to include the entire
County could provide a foundation to guide future flood hazard management decisions.
Integrating the CFHMP into Plan 2015 will ensure consistency of land use recommendations
across both documents, and increase the importance of flood hazard management planning.
Expanding the CFHMP to include the entire County, and possibly the entire Yakima
watershed, will ensure that common goals and policies direct flood hazard management
decisions throughout the County.
Preferred Alternative
The preferred alternatives to address the diversity of opinions relating to river management
and County policy on flood hazard management are as follows:
• The County should continue CFHMP Advisory Committee meetings on an ad
hoc basis
• The County should adopt the CFHMP as part of Plan 2015 to ensure consistency
of land use recommendations and provide goals and policies to direct future
flood hazard management decisions
• The County should expand the CFHMP to include the entire County, as funding
becomes available, to provide consistent floodplain management across the
County
• The County should review other plans, such as the Yakima River Watershed
Management Plan currently being prepared by the Yakima River Watershed
Council, for consistency with the CFHMP. The County should participate in
other river management planning processes, and invite personnel from other
river interest groups to future CFHMP Advisory Committee meetings.
With the establishment of the Yakima County Flood Control Zone District, and the
staffing of the District by the Public Works Department, the lines of communication
between the County, State Agencies, the Yakama Nation, the Cities of Yakima, Union
Gap, Selah and others in the County have improved. The Flood Control Zone District is
involved in numerous planning and project activities in the County and in the Basin as a
whole. The FCZD is currently completing the Naches CFHMP, and will start on the
Ahtanum/ Wide Hollow CFHMP next, and the Lower Yakima CFHMP after that. The
CFHMP have not yet been adopted as a part of the Comprehensive Plan, such and
action may not be practical due to the wide variety of actions in a CFHMP which do not
relate to a comp Plan, but certainly the Comp Plan can refer to the CFHMPs as policy
guidance in implementation of the Comp Plan and CFHMP itself.
RW4 — Flood Hazard Ordinance (13), and
RW5 — Revision and Consistency of Critical Areas Ordinance (30)
Problem Definition
Flood damage prevention ordinances for jurisdictions in the study area are the basic regulatory
tools for flood hazard management. Yakima County incorporated flood hazard regulations
8-59
Draft Upper Yakima River Comprehensive Flood Hazard Management PIan Amendment.
into their recently adopted Critical Areas Ordinance (CAO). The CAO combined requirements
of the Growth Management Act, the Shoreline Management Act, and the National Flood
Insurance Program into one ordinance to limit the amount of regulatory redundancy and to
provide a single ordinance regulating environmental impact near the Yakima mainstem.
With the goal of attaining a regulatory program for flood hazard management that is
comprehensive, enforceable, and simple, the issue was raised of the inconsistency of ordinances
across political boundaries and the potential for ordinance enhancement to further reduce flood
hazards in the future.
Alternatives Analysis
Chapters 4 and 5 of the County's CAO address flood hazard management pertaining to
Hydrologically Related Critical Areas (HRCAs) and Flood Hazard Areas, respectively.
Floodways and the 100 -year floodplain are by definition included in HRCAs, and are therefore
subject to the regulations described in Chapters 4 and 5.
Chapter 4 of the CAO deals with requirements and conditions for receipt of a critical area
development authorization. This authorization is required before construction in a designated
critical stream corridor may begin. General development requirements include avoiding
contributions to stream degradation; conserving and protecting soils, surface water, subsurface
water, vegetation, and wildlife; avoiding degradation or impairment of the stream from the
cumulative impact of individual projects; and preserving natural conditions using native
vegetation unless manmade solutions better serve the purpose. In addition, designated Flood
Hazard Areas, as defined by FEMA, must comply with the standards in Chapter 5 of the CAO.
Chapter 5 of the CAO incorporates the County's Flood Hazard Ordinance (FHO), and supports
the minimum requirements established for participation in the NFIP. Some additions and
revisions have been made to the FHO to maintain consistency with the overall CAO.
To compare consistency of FHOs across jurisdictional boundaries and to identify possible
ordinance enhancements, Chapter 5 of the CAO was compared to the FHOs of the Cities of
Selah, Yakima, and Union Gap. In addition, comparisons were made to NFIP requirements and
the recommendations set by Ecology.
Each jurisdiction's ordinance fulfills the minimum requirements for participation in the NFIP.
However, variations occur beyond this minimum. Inconsistencies exist in areas such as type of
development allowed, setbacks and buffers, and required lowest floor elevations for structures
within the floodplain. Table 8-8 lists requirements of the County's CAO that differ from the
NFIP and other jurisdictions.
Ordinance Inconsistencies
The County makes a distinction between residential and non-residential construction elevation
requirements. For new residential development located between the 100 -year floodplain
boundary and a 100 -foot buffer from the floodway boundary, structures must be elevated to or
above BFE. For new commercial/industrial development in the same location, structures must
be elevated a minimum of 1 foot above BFE, or be floodproofed. This distinction is not present
in NFIP requirements; however, by requiring a more stringent standard, the County is
8-60
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
obtaining a higher degree of safety than required by the NFIP. A standard consistently applied
to both residential and non-residential structures would make the ordinance easier to
understand, to apply, and to comply with.
In the same clause, the County allows non-commercial development to apply floodproofing
techniques in lieu of elevation requirements. This allowance is deemed permissible by NFIP
minimum standards; however, those who choose to floodproof rather than elevate are assessed
higher flood insurance premiums based on the lower recorded building elevation. Thus, the
landowner incurs the cost of both increased insurance premiums and floodproofing tasks.
Depending on the level of risk the County assumed when creating this regulation, it may be
worth reconsidering the floodproofing clause and revising the ordinance to require all
non-residential development to elevate.
8-61
TABLE 8-8.
SUMMARY OF DIFFERENCES IN FLOOD HAZARD ORDINANCES FOR YAKIMA COUNTY, CITIES OF SELAH, YAKIMA, AND UNION GAP,
AND REQUIREMENTS OF THE NATIONAL FLOOD INSURANCE PROGRAM
Item
Yakima County
City of Selah
City of Yakima
City of Union Gap
NFIP
Title of Ordinance /
Regulation
General Standards for
Flood Hazard Zones
Specific Standards for
Residential Structures
Specific Standards for
Commercial,
Industrial, and Other
Non-Resid. Structures
Specific Standards for
Agverage Structures
Conditions for
exemptions from BFE
elevation
requirements
Specific Standards for
Manufactured Homes
Yakima County Critical Area Ordinance,
Ordinance No. 8 -1995, Section 5
All development within 100 feet of the
floodway (or OHWM if no floodway exists)
must be elevated to Base Flood Elevation
(BFE) using zero rise methods, unless
nonzero -rise methods do not impede
movement of floodwater
Roads and utilities serving proposed
subdivisions must be located and constructed
to minimize flood damage
New construction and substantial
improvements must elevate the lowest floor
to or above the BFE
Fully enclosed areas below lowest floor
prohibited unless they equalize hydrostatic
forces by allowing entry and exit of
floodwaters. Such designs must be certified
Comply with standards for development
within 100 feet of floodway/OHWM
Low potential for flood damage
Structure is designed to allow free passage of
water
All electrical and mechanical equipment is
elevated to a minimum of one foot above BFE,
or floodproofed
Buildings are placed on site to offer minimum
resistance to flood
Buildings will not be used for human
habitation
Must be elevated to or above BFE, and must
be anchored to a foundation system
Flood Hazard
Protection - Chapter
11.19
Not specified
Section 11.19.060(d)(2)
Section 11.19.065(a)(1)
Section 11.19.065(a)(2)
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Section 11.19.065(c)
Flood Hazard
Protection - Chapter
11.58
Not specified
Section
11.58.140(4.1,4.3,4.4)
Section 11.58.150(1.1)
requires elevation 1 foot
or more above BFE.
Section 11.58.150(1.2)
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Section 11.58.150(1)
requires elevation to 1
foot or more above BFE
Flood Hazard
Protection - Chapter
14.28
Not specified
44 CFR 59 - 77, National
Flood Insurance Program
Not required
Section 14.28.170(a,c,d) Exceeds Section 60.3 (a)(4)(3)
Section 14.28.200(a)
Section 14.28.200(b)
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Section 14.28.220
requires elevation to 1
foot or more above BFE
Section 60.3(c)(2)
Not Required
Not required
Not required
Not required
Not required
Not required
Not required
Section 60.3(c)(6)
11111— all 11111 11111 NM— NM M-- En —— UN— M NW
S MI M N MO IIIIIII 11111 111111 111M1 11111 MN NM 111111
TABLE 8-8 (continued).
SUMMARY OF DIFFERENCES IN FLOOD HAZARD ORDINANCES FOR YAKIMA COUNTY, CITIES OF SELAH, YAKIMA, AND UNION GAP,
AND REQUIREMENTS OF THE NATIONAL FLOOD INSURANCE PROGRAM
Item Yakima County City of Selah City of Yakima City of Union Gap NFIP
Floodway Fringe
Permitted Uses
Any use normally permitted by County Not specified Not specified Not specified Not required
Zoning or Yakima Urban Area Zoning
(includes both underlying zone and
floodplain overlay zone)
Utility transmission lines permitted when Not specified Not specified Not specified Not required
primary purpose is to transport bulk energy
products
Transmission lines permitted to cross Not specified Not specified Not specified Not required
floodway fringe by most direct route
In channel migration areas, buried hazardous Not specified Not specified Not specified Not required
material transmission lines permitted if
placed at a minimum depth of four (4) feet
In non -channel migration areas, buried Not specified Not specified Not specified Not required
hazardous material transmission lines
permitted if placed below existing natural
and artificial drainage features according to
standard practice and soil conditions
Transmission lines in floodway fringe Not specified Not specified Not specified Not required
permitted if floodproofed
Above -ground transmission lines (not Not specified Not specified Not specified Not required
including electric) permitted for non-
hazardous materials
Floodway Fringe New mobile home parks or expansion of Not specified
Prohibited Uses existing mobile home parks prohibited
Utility appurtenances (pump stations, valves, Not specified
control facilities) prohibited, except where no
alternative is available. Exceptions must
prove no appreciable effect on flood depth,
and must be floodproofed
Floodway All uses permitted under County Zoning or Not specified
Permitted Uses Yakima Urban Area Zoning that meet general
standards and have a negligible effect on the
floodway are permitted
Surface mining permitted with evidence that Not specified
it will not divert flood flows, accelerate
flooding, or increase threats to upstream
areas. Mass removal must comply with the
Shoreline Management Master Program
Not specified Not specified
Not specified Not specified
Not specified
Not specified
Not required
Not required
Not specified Not required
Not specified Not required
TABLE 8-8 (continued).
SUMMARY OF DIFFERENCES IN FLOOD HAZARD ORDINANCES FOR YAKIMA COUNTY, CITIES OF SELAH, YAKIMA, AND UNION GAP,
AND REQUIREMENTS OF THE NATIONAL FLOOD INSURANCE PROGRAM
Item
Yakima County
City of Selah
City of Yakima City of Union Gap
NFIP
Floodway
Permitted Uses
Utility lines permitted for purposes of serving
customers in the floodway
Utility lines permitted for transfer of bulk
power products if lines cross floodway by
most direct route
Electric transmission lines permitted if lines
span the floodway with support towers in the
floodway fringe areas
In channel migration areas, buried hazardous
material transmission lines permitted if
placed at a minimum depth of four (4) feet
below the established scour of the waterway
In non -channel migration areas, buried
hazardous material transmission lines
permitted if placed below existing natural
and artificial drainage features according to
standard practices and soil conditions
In agricultural areas in the floodway, buried
hazardous material transmission lines
permitted if placed at a minimum depth of six
(6) feet below ground surface
Above -ground lines for non -hazardous
materials (not including electric) permitted
where existing or new bridge or structure is
available and capable to support the line.
When the structure is elevated below BFE, the
transmission line must be placed on the
downstream side of the structure and
protected from flood debris
Improvements to existing residences that are
not classified as "substantial" under the CAO
are permitted
Dikes are permitted, provided adverse effects
on adjacent properties do not result in
increased floodwater depths and velocities,
natural drainage ways are minimally affected,
and proposal is coordinated through
appropriate diking district(s)
Roads and bridges are permitted
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Not required
Not required
r11111— r■r — all all MN— I MI MI NM ■■M r— r 11111 I
IIIIII S S MI N M M MI M V MI N OM r MI M MI all
TABLE 8-8 (continued).
SUMMARY OF DIFFERENCES IN FLOOD HAZARD ORDINANCES FOR YAKIMA COUNTY, CITIES OF SELAH, YAKIMA, AND UNION GAP,
AND REQUIREMENTS OF THE NATIONAL FLOOD INSURANCE PROGRAM
Item
Yakima County
City of Selah
City of Yakima
City of Union Gap
NFIP
Floodway
Prohibited Uses
Procedure
Construction or storage of objects subject to
flotation or movement during flood periods is
prohibited
Filling of wetlands is prohibited unless
otherwise permitted by the CAO
Solid waste landfills, dumps, junkyards, and
outdoor storage of autos are prohibited
Damming/relocation of watercourses that
would result in downstream increases in BFE
are prohibited
Utility appurtenances (pump stations, valves,
control facilities) are prohibited
Variances allowed, but limited to
considerations of elevation requirements for
the lowest floor, elevation requirements for
floodproofing, and type/extent of
floodproofing
Variances not considered for procedural
issues or use prohibitions
Appeals process for variances established
through County Hearings Examiner
Not specified
Not specified
Not specified
Not specified
Not specified
Section 11.19.050(d)
allows variances for lots
of 1/2 acre or less
contiguous to and
surrounded by lots with
existing structures
constructed below BFE
Not specified
Not specified
FIRM revisions/ amendments referenced, and Not specified
subject to federal regulations
Not specified
Not specified
Not specified
Not specified
Not specified
Section 11.58.130(5)
allows variances for lots
of 1/2 acre or less
contiguous to and
surrounded by lots with
existing structures
constructed below BFE
Not specified
Section 11.58.130(1)
establishes process
through City Hearings
Examiner
Not specified
Not specified
Not specified
Not specified
Not specified
Not specified
Section 14.28.120(c)
allows variances for lots
of 1/2 acre or less
contiguous to and
surrounded by lots with
existing structures
constructed below BFE
Not specified
Section 14.28.110
establishes process
through City planning
commission and City
Council
Not specified
Not required
Not required
Not required
Not required
Not required
Section 60.6(a)(2) allows
variances for lots of V2 acre
or less contiguous to and
surrounded by lots with
existing structures
constructed below BFE
Not required
Not required
Section 70.1 - 70.9
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
The County's CAO designates agricultural land use as a separate use category and permits
non -habitable agricultural structures in the floodplain if they are floodproofed or elevated to or
above BFE. This agricultural distinction is not present in either NFIP requirements or Ecology's
model ordinances. It may be worth reconsidering the floodproofing clause and adjusting the
elevation requirement to accord with that for residential and commercial/industrial uses.
Within a 100 -foot buffer from the floodway, all structures must be elevated to BFE using zero
rise methods. Yet beyond the setback, commercial/industrial structures would be required to
elevate to one foot above BFE. There is also a discrepancy in elevation requirements for
manufactured homes. Yakima County and Selah require manufactured homes to be elevated to
or above BFE, while the cities of Yakima and Union Gap require these structures to be elevated
1 foot or more above BFE. Consistency in elevation requirements is needed across County and
City jurisdictional boundaries.
Requirements in Chapter 4 of the CAO for siting utility lines in HRCAs duplicate those
requirements in the floodway fringe and floodway in Chapter 5. Since the floodway is by
definition an HRCA, it seems that the specific requirements of Section 5.32.010 (2) and Section
5.36.010 (2), pertaining to siting of utilities in the floodway fringe and floodway, could be
consolidated with Section 4.14, pertaining to siting of utilities in HRCAs.
Chapter 5 of the CAO permits surface mining provided there is evidence that it will not divert
flood flows, accelerate flooding, or increase threats to upstream areas. Chapter 4 allows
industrial mining of gravel, but requires authorization by the County, Ecology, and WDFW,
and excludes such activity from the 100 -foot "zero -rise" buffer area. These conflicting
descriptions of mining activity should be rectified and presented as a single comprehensive set
of standards in Section 4.18.
Ecology's model ordinance recommends the use of an optional clause promoting siting of
critical facilities outside the floodplain, and outlining elevation and floodproofing conditions
for critical facilities constructed within the floodplain. Chapter 5 does not contain this optional
provision, which should be considered for inclusion.
Flood Hazard Areas in the CAO are adopted by reference to FEMA's Flood Insurance Study
(FIS) dated June 21, 1984, and accompanying Flood Insurance Rate Maps (FIRMs) and Flood
Boundary and Floodway Maps, and any amendments made thereafter by FEMA. This does not
take into account new information collected and developed in the 1995 FIS and displayed on
the 1995 preliminary revised FIRMs. Specific reference should be made to sources of new
information. All elevations, zone determinations, and floodway setback determinations should
be based on the newly revised 1995 FIRMs or newer information, and be specifically pointed
out in the ordinance.
Yakima County maintains a 100 -foot zero -rise buffer area surrounding the OHWM or
regulatory floodway. In many cases, the County's CAO will apply only to the east bank of the
river. The west bank of the river will be regulated by varying requirements of City ordinances,
none of which include zero -rise methods.
8-66
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Preferred Alternative
The following actions are recommended to increase regulatory consistency and reduce future
flood hazards as discussed above:
• Sections 5.28.020(1)(a), 5.28.020(2), and 5.28.020(3) of the County's CAO should
be revised to require all new construction and substantial improvement,
regardless of intended land use, to be elevated or floodproofed 1 foot or more
above the revised BFEs, and be accessible to emergency vehicles during a flood
• CAO Sections 5.32.010(2) and 5.36.010(2) pertaining to requirements for siting
utility lines in the floodway fringe and floodway should be consolidated within
Section 4.14 pertaining to siting of utilities in HRCAs. The existing sections in
Chapter 5 should reference standards set forth in Section 4.14
• CAO Section 5.36.010(1) should be deleted. Provisions requiring evidence that
surface mining will not divert flood flows, accelerate flooding, or increase
threats to upstream areas should be relocated to Section 4.18.040. Surface mining
in floodway fringes and floodways would change from a permitted use as
described in Section 5.36.010(1) to a conditional use as described in Section 4.18
• A new CAO Section 5.28.010(d) should be added as follows:
(d) Critical Facilities
Construction of new critical facilities shall be, to the extent possible,
located outside the limits of the base flood plain. Construction of new
critical facilities shall be permissible within the base flood plain if no
feasible alternative site is available. Critical facilities constructed within
the base flood plain shall have the lowest floor elevated to 3 feet or more
above the level of the base flood elevation at the site. Floodproofing and
sealing measures must be taken to ensure that toxic substances will not
be displaced by or released into floodwaters. Access routes elevated
2 feet or more above the base flood elevation shall be provided to all
critical facilities to the extent possible.
Add the following definition to CAO Chapter 2:
Critical Facility means a facility for which even a slight chance of
flooding might be too great. Critical facilities include, but are not limited
to, schools; nursing homes; hospitals; police, fire, and emergency
response installations; and installations that produce, use, or store
hazardous materials or hazardous waste.
• Revise CAO Section 5.20.010 to reference the 1995 revised FIS and FIRMs or the
best available information.
• The County should determine if each jurisdiction's shoreline ordinance requires
mitigation similar to zero -rise methods for the area within 100 feet of the
OHWM or floodway. If so, language from the shoreline ordinances should be
repeated in each jurisdiction's flood hazard ordinance. If not, Yakima County
CAO Section 5.28.010(a)(3) should be replicated in each jurisdiction's ordinance
8-67
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• City jurisdictions should integrate flood hazard items included in the County's
CAO that are not specified in their respective FHOs or CAOs or develop an
inter -local agreement creating a FHO that applies across all jurisdictional
boundaries.
The primary benefits of these alternatives are regulatory clarity, elimination of redundancy,
consistent floodplain management, and a possible decrease in future flood hazards if
enhancements are adopted.
The Flood Control Zone District is currently tracking the update of the Comprehensive Plan
and implementing regulations (Critical Areas, Floodplain, Zoning) of the County and Cities for
consistency with the above recommendations.
LR3 —Increased Flood Elevation near Union Gap (14)
Original Priority: 14 of 39
Amendment Priority: 3 of 39
Problem Definition
Continued confinement of Yakima River floodwaters between levees can have an impact on
flood elevations downstream. Solving upstream flood problems can move the flood problems
downstream; therefore any flood hazard management alternative needs to consider the
downstream impact. The City of Union Gap and residents in the Lower Valley are concerned
that the elimination of Upper Valley floodplain storage will result in increased flood elevations
downstream.
More precisely, the City of Union Gap and residents in the City and adjacent areas are
concerned that flood elevations have been rising over time, effecting existing and potential land
uses as well as flood hazard.
Discussion of Alternatives
To investigate trends in flood elevations, historical high water elevations from similar flood
events were compared. High water elevations for the November 26, 1990, flood were compared
to those for the November 30, 1995 flood. Results are shown in Figure 8-5 and Table 8-9.
High water elevations do not differ significantly between the two floods. They generally fall
within the range of 1.3 feet higher to 1.3 feet lower, depending on the location. This variability
could be attributed to channel aggradation or degradation, or a slight difference in high water
elevation location. The largest elevation difference is near river mile 110. At this location, the
1995 high water elevation was 3.8 feet lower than the 1990 flood elevation, possibly due to
channel degradation. The minimum elevation difference is at the USGS gauging station near
Union Gap, where no significant water level difference was measured between the two floods.
The data are inconclusive for detecting a definite trend in high water elevations, specifically
near Union Gap. Large differences in high water elevations were not expected, given that a
large flood did not occur between the two flood events, and no major floodplain modifications
8-68
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
took place. A greater concern is the cumulative change over longer periods of time. Larger
changes in high water elevations might have been observed had earlier data been available.
High water data before and after Yakima Valley levee construction may show an increase in
flood elevations and inundation area in the Lower Valley, given the cumulative loss in
upstream floodplain storage. The cumulative effect of continued floodplain encroachment is
probably contributing to increased flood elevations downstream; however, this is not
supported with the limited flood elevation data available.
Yakima County
UPPER YAKIMA RIVER CFHMP
KCM
1090.0
1070.0
1050.0
1030.0
0
1010.0
LL]
990 0
970.0
950.0
ONov 95 Flood
Flow=36,000 cfs)
- - - 26 Nov 90 Flood
(Flow=35,620 cfs)
on
r. 0)
CO v
00 to
v
N
106 108 110
Terrace Hgts Bridge
112 114 116 118
River Mile
Figure 8-5
COMPARISON OF HIGH WATER ELEVATIONS ALONG THE YAKIMA RIVER
Flood Control Zone District staff investigated the hydraulic and sediment transport conditions
in this reach (channel confinement, rates of sediment accumulation and meander movement),
and determined that it is likely that this area is experiencing sediment aggradation. This
aggradation is to be expected given the hydraulic influence of Wapato Dam located just
downstream from Union Gap (see Figures A8-12 & 13).
8-69
While it is probably not possible to accurately estimate the degree to which flood elevations
have risen in this location, due to the large shift in river location that occurred in 1972, some
general observations can be made. Comparison of the water surface elevations shown in the
as -built drawings for I-82 which was finished in 1968 with current conditions indicate that the
current water surface elevation (at normal summer flow) is a minimum of 2.7 feet higher than it
was in 1968. If you assume the standard specifications for installation of culverts were used as
shown on the plan, and know the dimensions and elevations of the culverts which were
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Elevation
Selah Gap and Union Gap Profiles
l -10D000
940 000
910.000
OCIMP
-8000 000 -6000 000 -4000 000 -2000 000 0.000 2000 000 4000 000
Distance from Narrow Pt
—•-- Selah Gap
Union Gap
Figure A8 12. Comparison of the water surface Gradients of through Selah Gap and
Union Gap. These are profiles generated from the LIDAR data; the zero point is the
narrowest point within either gap to facilitate comparison. Note how far upstream
from Selah Gap the river gradient increases, at Union Gap the gradient is flat, the
difference between the two indicates the amount of sediment deposition upstream
of Union Gap.
Will Add Later
Figure A8-13 100 -year flood profile through Union Gap. This is from Dunne and
Leopold and is based on the 1984 Corps flood model. Note how far upstream
Wapato Dam influences water surface slope, and therefore sediment transport
capacity. Given this graphic, sediments can be expected to accumulate upstream of
Wapato Dam.
8-70
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
installed to carry Spring Creek back under I-82 to the freeway, the rise in water surface
elevation at that specific location would be approximately 3.8 feet. This corresponds well with
the cross-sections derived from the LIDAR data shown in Figures A8-14 and A8-15.
Cross Section
Union
Farms
A8-14 Cross -Section Location. Note Union Farms, multiple River channels, I-82,
and Spring Creek. Levees shown in red cross hatch.
8-71
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
0
U
c
_
972.000
970.000
968.000
966 000
964 000
962.000
960.000
958.000
956.000
Levees At
Union
Farms
Cross Section # 25
0.000
1000 000 2000.000
3000.000 4000 000
Elevation
5000 00
6000 000
Yakima River
Channels
7000.000
A8-15 Cross -Section of Floodplain Near Union Gap. Note that the floodplain left
(east) of I-82 is higher than the Spring Creek Floodplain right (west) of I-82.
—4,— ELEVATION
-Spring
Cr.
Preferred Alternative
Future flood hazard management measures should ensure minimal increases in downstream
flooding. If no action is taken, decisions could be made without considering the effects on
downstream flooding conditions. To limit the possibility of worsening flooding conditions in
other areas of the Yakima Valley, the following actions are recommended:
• Develop a high water elevation database to evaluate changes in river channels
and trends in high water elevations. The database could include flood elevations
8-72
Given that there is strong indication that this reach of the river has aggraded almost 4.5
feet since 1968, and that there is only 4 feet from the normal water surface elevation to
the surface of I-82 (which acts as a levee and protects large areas of the City of Union
Gap) addressing this item is a high priority. Additionally, sediment accumulation in
this, the most valuable fisheries habitat portion of the reach, has negative consequences
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
over time at a specific location, historical aerial photographs, changes in
surveyed river cross-sections, and the historical record of flood damage areas.
• Adopt and follow the proposed Plan 2015 County policy to "protect the
hydrologic functions of natural systems to store and slowly release floodwaters,
reduce flood velocities, and filter sediment." Protecting the natural storage
function of the Yakima River floodplain will reduce the potential for increased
flood elevations near Union Gap and in the Lower Valley.
• Add compensatory storage requirements to the County's CAO. This
requirement is a method of reducing the effects of filling in the floodplain.
Whenever fill material is added, the area that the fill occupies is removed from
the potential flood storage area. Under compensatory storage requirements, an
individual placing fill in the floodplain must excavate an area of equivalent
volume to eliminate the effects of the fill on flood storage.
TABLE 8-9
YAKIMA RIVER HIGH WATER ELEVATIONS
Cross-section
Location
(river mile)
Location Description
November 30, 1995
Flooda
(Flow=36,000 cfs)c
November 26, 1990
Floodh
(Flow=35,620 cfs)
117.20
115.78
114.55
113.27
Left side of Harlan Landing access road 1079.5
Upstream end of R Street parking area 1064.1
Left river bank x 900 feet downstream of
Burlington Northern Railroad bridge
Terrace Heights bridge 1028.5
1009.6
1048.4
112.52 Left bank levee 1,000 feet upstream of
Blue Slough closure structure
111.58 KOA campground levee downstream of
power pole
110.07 Left bank levee 3,000 feet downstream
of SR 24 bridge
107.27 Union Gap upstream of SR 12 bridge
(USGS gauging station)
a.
a.
a.
a.
SOURCE: 1995 Field Survey
SOURCE: COE 1990
Peak flow reported at Parker gauge.
SOURCE: USGS gauging station data.
1079.2
1065.1
1047.1
1029.6
1009.0
1003.3 1004.6
994.2 998.0
950.4d 950.4 d
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
on fish habitat in this reach, and the reach downstream by starving it of sediment. In
conversations with BIA, who operate the Wapato Dam, sediment accumulation has also
made the dam more difficult to operate as a piece of irrigation infrastructure (the
upstream pool is being lost, reducing the capacity of the channel to route water toward
the irrigation intake), and increase the damage the dam sustains during flood events
(the water surface slope is becoming steeper, resulting in greater scour at the dam toe,
and more damage from bedload passing over the dam. For these reasons, the BIA is in
favor of replacing or modifying the Wapato Dam to pass sediment more efficiently
(Harrison, personal communication), but has been unable to obtain funding to do so.
The Flood Control Zone District should work with BIA, BOR, and other interested
parties in replacing or modifying Wapato Dam to pass bedload. This will reduce or
reverse the rising of the riverbed and flood elevations upstream of Union Gap, improve
fish habitat and riverine function for several miles upstream and downstream of
Wapato Dam, improve the Dam's primary function as irrigation infrastructure. It
would also reduce risk and damage to Wapato dam from floods, which is in and of
itself an extremely high flood hazard (can you imagine the economic havoc?) to
adjacent property owners, the agricultural community, and the Yakama Nation.
While Wapato Dam has a large influence on this reach, there is little doubt that loss of
floodplain upstream from Union Gap has resulted in a greater amount of sediment available to
deposit at this location. Action items to increase net floodplain area available for storage
associated with Issue LR5 will also aid in reduction of the rate of sediment deposition in this
reach.
The levees at Union Farms also act as a choke point in this section of the river forcing the river
against I-82, and taking a fairly large amount of floodplain surface out of the active floodplain.
Removal of these levees would relieve the pressure against I-82 by allowing the river to expand
across a larger floodplain.
RW14—Use of Nonstructural versus Structural Flood Control (15)
Problem Definition
Structural flood control measures are approaches that physically control how flooding occurs
and its effects on the natural and built landscape. Structural measures typically involve
engineering and construction activities to control floodwater. Nonstructural measures reduce
hazards associated with flooding by reducing the likelihood that people and property will
come into contact with floodwaters. Nonstructural solutions can involve drainage and land use
regulations, flood preparedness programs, public education, or maintenance programs.
8-74
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Historically, structural measures have been used in the Yakima Valley for flood hazard
management. Advisory Committee members have raised the possibility of integrating more
nonstructural alternatives into the County's flood hazard management program.
Discussion of Alternatives
If no action is taken, structural flood control measures may continue to be given greater
consideration in determining flood hazard management alternatives. This may result in higher
cost per public benefit received, or possibly ignoring a simpler solution. Nonstructural
alternatives require limited expenditure and are frequently easier to implement than capital
projects. They are typically more permanent and result in less environmental impact.
Policies being developed at the national level promote the use nonstructural measures to
mitigate flood hazards. Federal interests are promoting greater state and local mitigation
capability. A model has been developed to reward local governments that take measures to
reduce dependence on a federal system of flood hazard management and disaster recovery.
Federal funding is likely to become a function of the amount of flood hazard planning a local
community has performed; if a community is actively implementing higher regulatory
standards, public education programs, or a mitigation plan, federal funding in the future is
likely to be higher than for a community performing limited flood hazard management. This
provides an additional incentive to promote low-cost nonstructural alternatives.
Preferred Alternative
To provide an effective balance between structural and nonstructural alternatives, it is
recommended that the County adopt the CFHMP as part of Plan 2015, actively implement the
CFHMP, which is primarily nonstructural, and follow the CFHMP objective of giving
preference to nonstructural flood management measures in future flood management decisions.
No Change
RW2 — Loss of Fisheries Habitat and Riparian Areas (16), and
MR8 — Borrow Pit Levee Upstream of Terrace Heights Bridge (36)
Problem Definition
The Yakima River supports populations of spring and fall Chinook salmon, coho salmon, and
steelhead trout. The historical floodplain has been significantly modified, with development
resulting in the loss of off -channel rearing habitat for fish and riparian habitat for wildlife.
Channel complexity has been reduced, causing loss of critical rearing and spawning habitat for
salmonids. Further encroachment of the floodplain would reduce fisheries habitat, riparian
buffers, and floodplain storage. One identified encroachment is the old borrow pit levee on
DOT property upstream of the Terrace Heights Bridge.
Discussion of Alternatives
Fishery run sizes show continual decline over time (Table 8-10). Current run sizes are
estimated to be 1 to 0.4 percent of historical levels. The number of fish has drastically declined
8-75
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
due to a variety of causes, including low stream flows, impassable dams, loss of habitat, fishing
preserves, and poor water quality.
Opportunities are available to enhance fish habitat as well as increase floodplain storage for
flood reduction. The availability of areas to re-establish backwater channels is one opportunity
to improve salmonid spawning and rearing as well as floodplain storage. Several studies have
documented the use of backwater channels to increase overwinter survival and growth of
juvenile coho salmon (Cederholm 1991; Bonnel 1991). The technique involves grading down,
deepening, and widening relic side -channels on river floodplain to intercept subsurface flow,
or constructing channels to interconnect existing floodplain ponds that allow flow outside of
the main channel (Figure 8-6). Channels are often located to take advantage of existing roads,
railways, or levees so that floodwater does not enter at the upstream end. Re-established
backwater channels increase overwinter survival, increase the growth rate of juvenile salmon,
and provide a net benefit in fish production, as well as providing backwater flood storage.
Areas that exhibit potential for use as backwater channels include the following:
• Selah gravel pit following gravel extraction
• The abandoned mid -channel borrow pit upstream of Terrace Heights bridge
• Yakima Beach Street Gravel Pit
• Newland gravel pit following gravel extraction
TABLE 8-10.
HISTORIC AND CURRENT RUN SIZES TO THE YAKIMA RIVER
Species Lowest Historic Estimatea Current 1995 Estimate
Summer Chinook 107,780 0
Spring/Fall Chinook 80,460 1,727h
Coho 40,280 633c
Sockeye 20,620 0
Steelhead 21,940 918
Total 271,080 3,278
a. SOURCE: McNeil 1993
a. 644 spring Chinook, 1,081 fall Chinook
a. All hatchery fish, wild stock extinct since approximately 1984.
Assistance is available under Section 1135 of the Water Resources Development Act (Public
Law 99-662) to provide funding to modify structures of a COE project to restore fish and
wildlife habitat. Fish and wildlife benefits must be associated with past COE projects in the
Yakima Valley. The extensive COE levee project within the CFHMP study area provides a
specific opportunity to apply this program. Planning studies, detailed design, and construction
are funded with a 75 percent federal cost -share. The program requires a non-federal sponsor to
contribute the remaining 25 percent funding match. The potential sponsor requests by letter
that the COE initiate a feasibility study. Following receipt of the letter of intent, the COE will
request study funds.
8-76
Levee
Abandoned
Borrow Pits
Existing
Backwater
Channel
Constructed
Interconnecting
Channels
n
co
Abandoned
Oxbow Lake
co
1917 First Avenue
Seattle, Washington 98101
Yakima County
UPPER YAKIMA RIVER CFHMP
Constructed
Egress Channel
Figure 8-6.
BACKWATER CHANNELS FOR
FISH HABITAT ENHANCEMENT
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Preferred Alternative
If no action is taken, run sizes may continue to decline, as will areas for floodplain storage.
Opportunities are available to increase floodplain storage while enhancing fish habitat through
the use of backwater channels. This is consistent with the CFHMP objective to adopt flood
control measures that preserve or enhance existing fishery, wildlife, and other natural uses of
the riparian zone. To mitigate loss in fish habitat resulting from past and future flood control
measures, the following are recommended:
• The County, WDFW, and the Yakama Indian Nation should identify and
specifically list fish habitat enhancement areas that are consistent with
comprehensive floodplain management planning and could be quickly acted
upon as funding becomes available.
• The County should submit a letter of intent for participation in the COE 1135
program to obtain funding for fish habitat restoration. WDFW and the Yakama
Indian Nation should act as the lead agencies in identifying enhancement
opportunities, with the County providing a support role. Prior to submitting a
letter of intent, the County, the Yakama Indian Nation, and WDFW should agree
on who will provide the 25 percent matching funds.
• The County should incorporate fish habitat enhancements or mitigation into
future flood hazard management projects and gravel pit reclamation by using
backwater channels, riparian planting, and placement of large woody debris.
The structural modifications to the levee system and other infrastructure which are
outlined above are consistent with this direction.
RW17—Existing Structures in the Floodplain (18)
Problem Definition
Numerous structures currently exist in the Yakima River floodplain. Many of the structures
were built prior to flood hazard ordinances and have no floodproofing or flood protection.
Therefore, these structures experience repetitive flood damage; the severity of flood damage
depends on structure location and elevation relative to flood elevations. If the flood risk is not
reduced, damage can be expected to continue, which could result in public expenditures.
Discussion of Alternatives
As part of the CFHMP, a floodplain survey was conducted from Selah to Union Gap. The
survey consisted of a field reconnaissance and review of aerial photographs to identify the
number of structures in the floodplain, their location, current use, type of construction and
foundation, and height of the first floor above ground level. Floodplain survey data sheets are
included in Appendix I.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
The survey identified, by quarter section, the number of structures within the floodplain. Table
8-11 and Figure 8-7 summarize survey results. A total of 609 structures were identified within
the surveyed floodplain. Of the identified structures, 54 percent are residential, 38 percent
commercial, and 8 percent agricultural. The highest concentration of structures exist in Selah,
East Selah, Terrace Heights, and near SR 24. Overall, structures exhibit minimal floodproofing.
TABLE 8-11
STRUCTURES IN THE FLOODPLAIN
Percent Percent Percent
River Reach Number of Structures Residential Commercial Agricultural
Yakima Canyon to Selah Gap 229 46 12 42
Selah Gap to SR 24 Bridge 313 58 6 36
SR 24 Bridge to Union Gap 67 57 7 36
Total 609 54 38 8
In the Selah and East Selah areas, 161 structures were identified in the floodplain; 51 percent
residential, 42 percent agricultural, and 7 percent commercial. Residential structures are
typically elevated 0.5 to 3 feet above ground level; agricultural structure are elevated 0 to 3 feet;
and commercial structures are elevated 0 to 4.5 feet. Residential structures are more densely
concentrated and consist largely of mobile homes (over 40 percent). Structures near Pomona
Road and Naches Avenue East experience greater flood damage due to frequent inundation.
In the Terrace Heights area, 112 structures were identified in the floodplain; 57 percent
residential, 41 percent agricultural, and 2 percent commercial. Residential structures are
typically elevated 0.5 to 2 feet above ground level; agricultural structure are elevated 0 to 1 feet;
and commercial structures are elevated 0.5 feet. Historically, structures near Keys Road have
experienced the most flood damage, but these are now protected by a certified levee.
Near and downstream of SR 24, 195 structures were identified in the floodplain; 58 percent
residential, 34 percent agricultural, and 8 percent commercial. Residential structures are
typically elevated 0 to 4 feet above ground level; agricultural structure are elevated 1 to 3 feet;
and commercial structures are elevated 0 to 2.5 feet. The highest density of structures is located
north of SR 24. Recent flood damage occurred to structures near First Street in Union Gap.
To address structures in the floodplain, several alternatives were evaluated, including the
following:
• Develop a public education program on floodproofing
• Perform a detailed flood audit of floodplain structures
• Participate in cost -share program (voluntary program as funding becomes
available) to floodproof existing floodplain structures
• Actively pursue funding through the Hazard Mitigation Grant Program for
structure acquisition
8-78
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
• Allow floodplain structures to continue to be damaged during flood events (no
action).
Citizens residing in flood -prone areas should be made aware of floodproofing techniques if
they desire to floodproof their homes. The County could make floodproofing references and
fact sheets available to citizens. Information can be obtained from the FEMA publications
Flood -Proofing Non -Residential Structures (FEMA 1986) and Design Manual for Retrofitting Flood -
prone Residential Structures (FEMA 1989), or from many of the publications distributed by
FEMA's outreach program. Floodproofing materials could be distributed with flood
information brochures to libraries, fire departments, chambers of commerce, and city offices
throughout the County. Educational material distribution would increase the probability of
educating property owners unfamiliar with preventative flood -control measures.
Detailed flood audits have also been used in the past to provide information on specific flood
hazards at habitable structures within floodplains. The goal of the flood audit is to provide
each resident with information on actions to take prior to, during, and after a flood that are
specific to their location and residence. The major activities of a flood audit include the
following:
• Field Reconnaissance: A field reconnaissance is performed to collect elevation
data and record structural characteristics of each specific structure.
• Nonstructural Evaluation Computer Program: A nonstructural evaluation
computer program, developed by the COE, uses the data collected in the field
and predictions of floodwater elevations to evaluate costs and benefits of a
variety of nonstructural flood reduction measures.
• Mailing to Floodplain Residents: A packet of materials is mailed to each
resident describing actions to take prior to, during, and after a flood; evacuation
routes; areas of floodwater inundation; neighborhood homes below flood
warning levels; and recommended nonstructural measures to floodproof their
home.
The County could work with the COE or FEMA to perform a flood audit or obtain the COE's
nonstructural evaluation computer program and perform similar flood audits in-house. Flood
audits could provide information on specific flood hazards at habitable structures within
floodplains and educate floodplain residents so that they may initiate corrective flood
protection measures.
Raising or moving structures also provides permanent flood protection to floodplain
structures. Relocation or elevation has high short-term costs; however, in the long term, these
actions may provide the lowest cost alternative in very high flood hazard areas. Several state
and federal programs are available to assist in this type of mitigation. Recent catastrophic
flooding in the Midwest resulted in a modified approach for state and federal buyout,
relocation, and floodproofing programs. The changed approach is reflected in new programs
targeted at mitigation and prevention of repetitive flood damage. A detailed description of
federal and state programs are included in Chapter 9, including funding options for program
implementation. The County could limit the amount of repetitive flood damage by pursuing
and implementing these types of programs.
8-79
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Preferred Alternative
If no action is taken, repetitive flood damage is likely to continue. Residents will rebuild
flood -damaged structures without taking measures to reduce the potential for future flood
damage. This will result in continued private and public expenditures for disaster relief.
To provide the greatest reduction of future flood damage to floodplain structures at minimal
cost, the following actions are recommended:
• The County should work with FEMA to make floodproofing references and fact
sheets available to citizens. Floodproofing materials could be distributed with
flood information brochures to libraries, fire departments, chambers of
commerce, and city offices throughout the County. Educational material
distribution will increase property owners' knowledge of preventative flood -
control measures.
• The County should pursue funding through the Reigle Community
Development and Regulatory Improvement Act, Robert T. Stafford Disaster
Relief and Emergency Assistance Act, and Flood Control Assistance Account
Program to provide cost-sharing to floodplain residents for floodproofing,
elevation, and relocation of previously flood -damaged structures on a voluntary
basis. Effort should focus on recently damaged property and mobile homes near
Pomona Road, Naches Avenue East, Keys Road, and First Street in Union Gap.
No Change.
RW16—Operation and Maintenance of Flood Control Facilities (21)
Problem Definition
The County routinely inspects federal flood control facilities and PL -84 -99 -eligible levees. The
County follows the 1955 Operation and Maintenance Manual (COE 1955), developed for federal
facilities, with a few modifications. A draft memorandum of agreement (MOA) between the
COE, Ecology, and WDFW guides the County on vegetation and habitat management for flood
control structures. In addition, the County performs levee maintenance under a modified
mitigated determination of nonsignificance (MDNS), which incorporates the MOA and
additional conditions. Therefore, maintenance of flood -control works is defined in several
documents; this produces the potential for inconsistency and inadequate clarity of maintenance
procedures and responsibilities. Specifically, the following operations and maintenance issues
have been identified:
• The 1955 Operation and Maintenance Manual does not reflect current conditions
• Detailed information on each flood control facility is not readily available
• Maintenance crews need additional guidance on vegetation maintenance
requirements for certain plant species
• County inspection forms are inconsistent with the identification system used by
the COE
8-80
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
• Maintenance requirements differ according to the type of structure. For
example, maintenance requirements differ for federal levees and PL84-99 levees,
as they do for basic levee sections and overbuilt levee sections. The different
types of structures are also not clearly defined in the maintenance procedures
• No policy exists describing the County's role in maintaining future flood -control
structures that are not constructed by the County.
Discussion of Alternatives
Many operations and maintenance issues could be resolved by updating and documenting
clear maintenance procedures for each flood -control facility in the County. Documenting this
information would eliminate outdated information, provide clear guidance to maintenance
crews, provide consistency for all agencies involved, and ensure adequate recording and repair
of identified deficiencies. This would ensure the proper operation of each facility and adequate
vegetation maintenance to benefit fish and wildlife. Several steps could be taken to better
define O&M procedures.
Conduct a Detailed Flood Control Works Inventory
Detailed information on each flood control facility is not readily available. Flood facility
information is scattered throughout COE and County reports, COE inventory records and
drawings, and surveying field books. As part of the CFHMP, the first step in compiling this
information was conducted. Historical information was collected on facilities located
throughout the County and placed in a database to provide a detailed record for each facility.
The information in this format is readily available for future maintenance or repair decisions.
Database information, supplied in Appendix D, includes the following:
• Facility name and location
• Type of structure
• Managing agency
• Physical characteristics (dimensions, construction material, elevations)
• Level of protection, freeboard, and internal drainage structures for levee facilities
• Agency responsible for maintenance, schedule of maintenance, and previous
maintenance performed
• Inspection deficiencies, if applicable.
The County should field -verify and update the database to reflect the most recent information.
In addition, the database could be expanded to include supporting documentation such as
drawings, survey data, maintenance reports, photographs, and references to specific
maintenance procedures. A file should be kept for each facility, updated by maintenance crews
after each inspection.
8-81
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Clearly Define Vegetation Maintenance Requirements
General vegetation management procedures are described in the draft MOA and MDNS. The
MOA recommends plant species, vegetation densities, and thinning requirements for levee
maintenance. However, vegetation maintenance requirements vary by type of levee section.
Each levee needs to be field -verified to check the type of levee section. Each levee should be
classified as a standard levee section or an overbuilt levee section per the MOA. Once this
classification is made, appropriate vegetation maintenance procedures can be applied.
In addition, maintenance crews need additional guidance on vegetation maintenance
requirements for certain plant species. Per the MOA, WDFW and the COE should aid in
determining plant species that support habitat and limit the structural impact on levees. The
County should work with WDFW and COE to better defined thinning, cutting, and planting
procedures for each facility. These procedures should be developed for each facility and
include photographs so that maintenance crews can clearly identify plant species that require
thinning.
Update the 1955 Operation and Maintenance Manual
The 1955 operations and maintenance manual is outdated. New facilities have been
constructed, and other structures are no longer needed. For example, the recently constructed
KOA levee is not included in the maintenance manual, and the stop plank closure structure
near Gordon Lake levee is no longer needed due to the construction of SR 12. The County
should evaluate the 1955 O&M manual item by item, remove outdated information, and update
sections to include new facilities and new procedures described in the MOA and MDNS.
Combine Maintenance Requirements into One Document
Once the 1955 O&M manual has been updated and specific vegetation procedures have been
defined for each facility, the requirements should be consolidated into one document. The
document would incorporate applicable procedures in the 1955 O&M manual, procedures
outlined in the MOA and MDNS, and site specific vegetation maintenance requirements. Prior
to implementation, the County should seek final approval from the COE and WDFW.
Standardize County Inspection Forms
The County inspects federal flood -control facilities semi-annually; PL -84 -99 -eligible levees are
inspected annually. The County maintains an inspection form for each facility. Confusion
arises in cross-referencing levee identifications on the County inspection forms and on COE
inspection forms — levee segments are identified with different numbers and at different
locations. The County should create an inspection form for each flood facility data sheet
included in Appendix D. Facility data sheets were based on COE data; therefore, creating
County inspection forms for each data sheet would provide consistency with the COE.
In addition, two levees are misclassified by the COE. The COE still lists the KOA levee as
under PL 84-99 status even though the COE has inspected and approved the levee as meeting
federal standards. The KOA levee, identified as PL99-YSEG7A on the data sheets in Appendix
D, should be changed to federally authorized status. The COE lists a federally authorized levee
8-82
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
as PL -84-99. This levee, identified as FED-LB1 on the data sheets, is identified as PL84-99
Segment 9 by the COE. The County should request that the COE also reclassify this levee.
Continually Update the Flood Control Works Inventory
The flood -control works database should be updated as information becomes available.
Following inspections or the collection of additional information such as elevations,
maintenance crews should routinely update the facility's file. This will provide a continuous
record of work performed on each facility.
Preferred Alternative
The following are recommended to address operations and maintenance issues:
• Consolidate maintenance requirements into one document following the steps
outlined above
• Adopt a policy requiring all new flood -control projects to define maintenance
responsibilities and a funding source for operations, maintenance, and repairs
before acceptance by the County
• Continually update and maintain a flood control facility inventory database to
document the current condition of each flood control facility.
The FCZD is currently undertaking all of the above recommendations.
RW10— Acquisition / Preservation of Floodplain Open Space (23)
Problem Definition
One option for preventive flood hazard management is the acquisition or preservation of open
space in and adjacent to the floodplain. The limited extent of development in the upper and
lower reaches of the study area provides an opportunity for acquisition of open space.
However, available incentives have not been communicated to private property owners, and
funding sources have not been identified for potential acquisition of property for open space.
Discussion of Alternatives
The need to restrict development in floodplain areas leads naturally to their use as open space.
Many open space preservation programs identify floodplain areas as high priority: land is
usually available, is often inexpensive, and is suitable for the development of trails, parks, and
natural interpretive areas. Several opportunities exist to expand open space within the Yakima
floodplain.
Open Space Taxation Program
Yakima County currently administers an open space taxation program under Ordinance
No. 4-1989, as amended. The program defines the floodplain as a priority open space resource.
Properties that meet open space criteria may be reclassified from their original designations to
open space. Land value is then reassessed, usually resulting in lower property taxes to the
landowner.
8-83
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
Figure 2-12 (Chapter 2) shows parcels within the floodplain registered as open space with the
County Assessor. These parcels are highly concentrated upstream of Selah Gap west of the
Yakima River and downstream of SR 24 east of the river. Participation in the open space
program is minimal between Selah Gap and SR 24. Within the study area's floodplain, parcels
designated open space make up over 34 percent of the land area. Therefore, a large portion of
the floodplain remains available for potential open space designation.
Yakima Greenway Foundation
The mission of the Yakima Greenway Foundation is to conserve, enhance, and maintain the
Yakima River corridor as a continuing, living resource for future generations. The Foundation
is guided by the Yakima Greenway Master Plan, originally developed in 1976 and recently
updated in 1995 (Appendix E). The Foundation is actively seeking to expand its 3,600 -acre
conservation area throughout the Yakima River corridor.
The Foundation's vision suggests additional development altematives within the Yakima River
corridor. Suggested Greenway enhancements that affect open space land use in the floodplain
include the following:
• Locate enterprises related to tourism and recreation between the Greenway and
the parkway, with industrial parks and residential communities located along
the eastern edge
• Integrate attributes of the Greenway into urban design and planning decisions
• Establish circulation routes between downtown Yakima and the Greenway
• Extend the Greenway corridor along the Yakima River from Selah north to the
Yakima River Canyon.
Yakima County has a number of options for involvement in implementation of the Greenway
Master Plan. Currently, the County maintains a Greenway Overlay Zone as part of the Urban
Area Zoning Code. The implications of the overlay zone are essentially similar to those of the
floodplain overlay: permitted uses that would ordinarily receive a Class 1 review are upgraded
to a Class 2 review, which requires submission of a site plan and review of the Planning
Department. The County has the opportunity to use the design guidelines proposed by the
Master Plan in the process of conducting Class 2 review. The County Zoning Code that applies
to areas outside the Yakima Urban Area does not contain provisions for overlay zoning.
Existing Public Use Parcels
Figure 8-8 shows the location of existing public use parcels within the study area. Owners of
public use parcels include Yakima County, City of Yakima, WSDOT, and DNR. Thirty parcels
are owned by the County. Table 8-12 lists County -owned parcels and describes their location.
Future development of some of these parcels is yet to be decided; therefore, this provides an
opportunity for designation to open space or integration into the Yakima Greenway.
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
TABLE 8-12
COUNTY -OWNED PARCELS IN THE FLOODPLAIN
Number of Parcels Location
1 West of SR 821, north of Corriedale Road
1 Adjacent to Harrison Road
3 East of SR 12/I-82 interchange
1 West of Hartford Road
1 Adjacent to Terrace Heights Boulevard
10 Near Keys Road
4 Near SR 24
2 Northwest of Thorp Road
Federally Funded Programs
As described in issue RW17—Existing Structures in the Floodplain, state and federal programs
are available to fund the acquisition of property for open space. The programs allow local
agencies to acquire homes or other structures and private property, if property owners agree,
for the purpose of reducing or eliminating risk and damage from future disaster events.
Normally, this requires a 25 percent local funding match. The County could limit future flood
damage by pursuing and implementing programs of this type.
Preferred Alternative
Preserving and promoting open space within the floodplain is consistent with the long-term
CFHMP objective of promoting floodplain uses compatible with periodic flooding.
Recommended actions to enhance open space within the floodplain include the following:
• The County should continue to operate and promote the Open Space Taxation
Program. A public awareness campaign should be conducted to promote the
program, especially to property owners in the middle reach of the floodplain.
General information on the program can be distributed with the floodplain
information mailing recommended in issue RW7 — Flood Insurance and Public
Education.
• Designate undeveloped County -owned parcels as open space or integrate these
parcel into the Yakima Greenway master plan.
• Apply design standard of the Greenway Master Plan during Class 2 review of
developments within floodplain or Greenway overlay zones.
• Extend Greenway overlay zoning beyond the Yakima Urban Area within
conservation, recreation, and natural areas designated in the Master Plan.
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A major change which has occurred since the original plan was written is the BOR's
YRBWEP program, which has purchased a relatively large amount of floodplain
property in the planning area. The Flood Control Zone District is continuing to work in
cooperation with the BOR, the Yakima Greenway, the City of Yakima, and Yakima
County Planning Department to provide alternative means of promoting open space
land uses in the floodplain through incentives, compensation, easements, and purchase.
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Pursue funding through state and federal programs to purchase high -hazard
floodplain properties or development rights for open space use. Acquisitions
should be focused on repetitive loss areas near Pomona Road and Naches
Avenue East.
RW19 — Flood Warning and Emergency Response (24)
Problem Definition
CFHMP Advisory Committee expressed a few concerns about the flood early warning system
in Yakima County. The following needs were identified:
• Better management of road closure information
• Increased flood warning, especially along tributaries
• Availability of flood response equipment such sandbags
• Better transfer of information from the Emergency Operations Center (EOC) to
public officials
• Better public education.
Discussion of Alternatives
The elements of an early warning system—flood forecasting, flood monitoring, flood warning,
flood response, and public education—are defined as follows:
• Flood Forecasting—determining meteorological conditions expected to cause a
flood, and predicting flood levels
• Flood Monitoring—spatially and temporally tracking flood conditions as they
develop
• Hood Warning—maintaining appropriate communications with key
government officials and the public to relay information about the magnitude
and extent of impending flooding
• Flood Response acting to mitigate or prevent property damage or threats to
public health due to floods (includes evacuations, rescue, establishment of
temporary shelters, and road closures).
• Public Education—community awareness and understanding of flood hazards
prior to flood events and knowledge of the appropriate actions to take during
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
flood emergencies. Public education is relevant to each of the elements
described above.
Early warning issues identified in Yakima involve public education, flood monitoring, flood
warning, and flood response. Public education is addressed in issue RW7—Flood Insurance
and Public Education. Several other alternative can be implemented to address the remaining
issues.
Installation and Real-time Use of New Staff Gauges
The Bureau of Reclamation (BOR) maintains numerous gauging stations on the Yakima and
Naches Rivers. Stage (river elevation) measurements are recorded at each station and
translated into flow using rating curves that relate the two variables. The majority of the
gauging stations transmit data hourly to BOR computers monitored in real-time by County
officials. Emergency management personnel feel that river information is sufficient and timely
for flood monitoring (Thompson, D., 6 May 1996, personal communication). However, limited
information is available for tributary creeks.
Data from automated real-time gauges in the upper Ahtanum (two exist), Bachelor, Wide
Hollow, and Wenas Creek watersheds could be used to predict the time and magnitude of
flooding along these tributaries. Installation of automated gauges would increase flood
warning, monitoring, and forecasting capabilities. Gauges could be installed as part of the BOR
system or to supplement existing USGS gauging stations.
Currently, the County relies on local observations of river stage and BOR readings from their
gauge stations. The County could formalize a system of dispatching field teams to critical
locations along rivers and creeks to supplement gauge data. A list of critical locations and
responsibilities of field teams should be prepared by the OEM and department of public works.
Field teams should be trained and assigned to complete specific tasks during flood events.
Appropriate procedures and methods of communication between river watch teams and the
EOC should continue to be refined based on available communication equipment and past
flood experience. During a flood event, field teams should communicate to the EOC
information on river stage, bank failures, culvert failures, overland flow, road closures, and
public and private property damage.
Stage and Inundation Database and Inundation Maps
The County and the public currently have no method of relating river stage to inundated areas
during flood events. County use of this relationship during flood events would result in flood
warnings and responses that are more timely and targeted at appropriate areas. The public
would use this information and the river stage information communicated in County flood
warnings to determine whether they or their property are at risk from flooding. Data from
hydraulic modeling and historical flood events should be used to develop a flood inundation
map that shows which areas would be flooded during flood events of various magnitudes.
The County should issue a preliminary inundation map based on FEMA mapping and all
available data and photography from past flood events. The map should display inundated
areas associated with flows ranging from minor to extreme flood events. A verbal description
of the extent of flooding from each size of event should be included on the map.
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Draft Lipper Yakima River Comprehensive FIood Hazard Management Plan Amendment.
The County should record the following information in a stage and inundation database during
each flood event:
• Stage, discharge, and time from all stream gauges
• Mapped areas of inundation corresponding to specific times, river stages, and
discharges during the flood event, based on reports from citizens and river
watch teams
• High water marks and associated peak stages and discharges from the flood
event
• Time and location of critical infrastructure and corresponding river stages and
discharges
• Time and location of overland flows and corresponding river stages and
discharges.
The database and inundation map should be updated with new information following each
flood event. Updated versions of the database and inundation map should be issued to the
public periodically.
Database of Time Delays of Flood Peaks
The greatest impact from flood events occurs during the flood peak. This makes predictions of
when a flood peak will reach a location particularly important. However, information on the
time delays of flood peaks (flood peak lag) between locations along the Yakima River has not
been compiled and made available for County and public use. Estimates of the flood peak lag
based on historical data would provide information for citizens and officials to use in timing
their response to flood events.
The County OEM should work with the BOR to obtain time delays in flood peaks between
locations along the Yakima River for floods of various magnitudes. This information should be
included in flood preparedness materials distributed to the public and to government officials.
The time that flood peaks occur at specific locations should be recorded by citizen volunteers
and river watch teams during flood events. This information should be incorporated into the
database of historical flood peak lags and used by the OEM to predict the timing of flood peaks
at downstream locations. This information should be included in flood warning statements.
Community Alert Network
Currently, OEM staff must make numerous telephone calls and fax information to a wide range
of individuals to inform them of flooding conditions and related actions. The system of manual
phone calls and use of a limited number of fax machines is time-consuming and inefficient.
Complete or partial automation of this system would allow a greater number of individuals to
be contacted in a shorter period of time and provide more time for OEM staff to pursue other
activities.
One option is to create an automatic telephone notification system, such as provided by the
Community Alert Network (CAN). CAN will store all relevant phone numbers in its database.
During a flood emergency, the OEM can contact CAN to record an emergency message, and
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
specify the phone numbers that should receive it. Phone numbers to be called can include all
residents in the vicinity of predicted flood damage, specific governmental personnel including
police, fire, public works, and political officials, or a combination. Appropriate phone lists
should be developed in coordination with CAN prior to the flood event. (County has
completed).
Another option is to purchase additional fax machines or computer systems that can quickly
fax emergency information to numerous people. This hardware should be installed at the EOC
so that updated emergency information can be quickly distributed to public officials.
Road Closure Database
Managing road closure information is difficult during a flood event. Road closures change
rapidly, so relaying accurate and timely information to the public can be a large task. An
option to manage this information effectively is to compile a road closure database prior to
flood events. The County should review past flood events and create a database that correlates
road closures with river stage and discharge. Having this database in place allows public
officials to respond quickly to potential road closures areas as the river stage approaches the
predicted closure stage. This would result in more efficient use of river watch teams and allow
more accurate and timely communication to the public on road closures.
Supply of Emergency Response Equipment
During a significant flood event, citizens typically express concern about adequate availability
of sandbags for flood protection. Historically, Yakima County OEM or Public Works supplied
sand for sandbags; however, Public Works does not supply sandbags, but OEM will deliver
sandbags to five stations for distribution. The County should adopt this as a formal policy.
The policy should continue to be communicated to the public so that they are aware of
availability or non-availability of sandbags from public agencies.
During the February 1996 flood event, County maintenance crews also had difficulty obtaining
an adequate supply of barricades for road closures. The County's supply was insufficient to
cover the extent of the February flood. The County should purchase additional barricades or
secure a private source of barricades for use during a flood event. Using a private source of
barricades seems most appropriate, since they will be used only during significant flood events.
If no action is taken, the current preparedness and warning systems would be activated in the
event of a flooding emergency. Residents would be notified of flood events primarily through
public announcements and outreach by the Yakima County Sheriff. The Office of Emergency
Management would operate its Emergency Operations Center (EOC) in cases of flood
emergency, using information obtained from Bureau of Reclamation and other sources to
advise evacuation and response. While the current early warning system is operating well
given existing resources, opportunities are available to increase flood warning efficiency and
therefore reduce flood damage.
Preferred Alternative
Implementation of the following actions are recommended to improve the level of flood
preparedness in the Yakima Valley:
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Draft Upper Yakima River Comprehensive FIood Hazard Management Plan Amendment.
Short-term
• Formalize procedures for dispatching field teams and volunteers to critical
locations along rivers and creeks to manually collect real-time river information
• Obtain and compile from the BOR time delays in flood peaks between locations
along the Yakima River for various flood magnitudes
• Review and compile information on past flood events to create a database that
correlates road closures with river stage and discharge
• Develop and communicate to the public a policy on sandbag distribution during
flood events (completed)
Long-term
• Develop a flood inundation map for distribution to the public
• Install real-time, automatic gauging stations within the upper watershed of
tributary creeks
• Create a Community Alert Network for use at the EOC.
lood response Plan.
RW7—Flood Insurance and Public Education (32)
RW18 — Community Rating System (25)
Problem Definition
The cost of federal flood insurance and the lack of knowledge about the federal flood insurance
program may limit homeowners from purchasing flood insurance. In addition, the lack of
public knowledge about flood hazards may result in lack of appreciation of the magnitude of
the flood threat and associated risks an individual property owner faces, thereby limiting
property owner involvement in the flood insurance program or taking proper steps to
floodproof their property. Lack of public education is displayed in a newspaper account
describing the November 1990 flood (Yakima Herald, November 28, 1990). Yakima Valley
residents were quoted as saying "I didn't even think of this [floodwaters] hitting us" and "We
didn't know what to do."
In addition, the County has not actively pursued participation in the federal Community Rating
System (CRS) program. The CRS program, administered by FEMA, provides a reduction in
flood insurance premiums for communities that initiate flood protection activities beyond the
minimum NFIP requirements, such as flood hazard management planning. Many of the
activities that earn credit through the program involve public education about flood hazards,
flood insurance, and flood protection.
Discussion of Alternatives
The overall benefit of increasing public education of flood hazards is the long-term reduction of
flood damage and possible reduction in flood insurance premiums. As shown in Table 8-13,
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
$437,525 has been paid in claims since 1978 for all jurisdictions in Yakima County. This is
equivalent to approximately $24,300 in claims per year. Comparing average annual claim
amounts to the annual premiums of $141,509 shows that Yakima Valley residents are paying
annual premiums over 5.8 times larger than average annual claims. This is significantly greater
than in Washington State as a whole (3.1) and other eastern Washington counties (3.2). This
shows that Yakima County residents are paying a larger portion for flood insurance. This may
be a result of Yakima County not experiencing a significant flood event between 1978 and 1994,
minimal citizen participation in the NFIP, or high flood insurance rates.
TABLE 8-13
NATIONAL FLOOD INSURANCE PROGRAM AS OF NOVEMBER 30,1995
Community
Current Total Dollars Paid
Number of Annual Coverage Claims Since 1978
Policies Premium (1,000) Since 1978
Yakima County 301 $110,578
(unincorporated)
City of Yakima 18 $4,871
City of Selah 5 $4,195
City of Union Gap 3 $769
County Total' 401 $141,509
Total for Eastern
Washington Counties'
Washington State Total 17,416 $6,539,474
3,897 $1,399,036
$20,446 67 $244,128
$1,215 4 $2,048
$523 30 $191,341
$142 0 $0
$26,168 102 $437,525
$291,719 709 $7,942,068
$1,493,557 3,953 $37,829,474
a. Includes unincorporated Yakima County and all incorporated areas within the County that
are participating in the NFIP.
a. Includes the following counties: Adams, Asotin, Benton, Chelan, Columbia, Douglas, Ferry,
Franklin, Garfield, Grant, Kittitas, Klickitat, Lincoln, Okanogan, Pend Oreille, Spokane,
Stevens, Walla Walla, Whitman, and Yakima.
Review of the data presented in Table 8-13 also reveals that the City of Selah's paid insurance
claims are high compared to the number of current polices. This may be attributed to repetitive
losses experienced near Naches Avenue East. In addition, the number of current policies in
Yakima County is low compared to the number of private parties requesting disaster assistance
following the February 1996 flood: 401 policies and 1,782 people requesting assistance. This
indicates the limited use of flood insurance throughout the County.
The CRS program gives communities credit for implementing flood reduction activities that
result in a reduction of flood insurance premiums. CRS credits are available for 18 categories of
flood hazard reduction activity. The number of credits received in each category depends on
the degree to which CRS objectives are achieved. The total number of credits earned in all
categories determines the class level assigned to the community. The CRS provides for 10
classes, Class 1 having the highest credit and Class 10 for communities receiving no credit. A
community is automatically a Class 10 community unless it applies for a CRS reclassification
and shows that the activities it is implementing warrant a better classification. A minimum of
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
500 points is needed to receive a CRS classification of Class 9, which will reduce premium rates.
Activities for which points are awarded under the CRS are shown in Table 8-14.
If the County submits CRS documentation for current flood reduction programs and various
alternatives recommended in this CFHMP, it is estimated that over 1,500 credit points would be
earned. This would give the County a Class 7 rating, potentially reducing annual flood
insurance premiums by 15 percent in addition to reducing the potential for flood damage.
A key element of the CRS is public education. The overall objectives of an educational program
for government representatives and local citizens include the following:
• Develop community awareness and understanding of flood hazards
• Provide instructions on where and when to obtain information during flood
emergencies
• Describe the appropriate actions in response to flood emergencies.
These objectives can be met through educational opportunities, including the following:
• Distributing educational material on preventive flood -control measures to
libraries, public offices, and chambers of commerce
• Publishing newspaper articles on flood hazard management and the County's
early warning system during the pre -flooding season
• Distributing flood inundation maps
• Developing and distributing a video on flood hazard management
• Publicizing and conducting emergency preparedness classes as developed by
FEMA and the Red Cross
• Conducting outreach programs to citizens in high flood hazard areas to educate
them on flood hazards, floodproofing, preparing for flood events, flood
insurance, floodplain development permit requirements, and natural and
beneficial functions of the local floodplain
• Holding annual flood exercises to exchange information among government
officials and review procedures in preparation for the flood season.
Dedicated staff is required to implement an effective public education program. The County
should dedicate a public education officer (PEO) to manage such a program. The PEO should
be trained in floodplain issues. PEO responsibilities would include managing and
implementing the educational opportunities listed above, in addition to administering the local
CRS. The PEO would coordinate with FEMA, Ecology, resource agencies, and local
departments of emergency management, public works, and planning.
If no action is taken, County floodplain residents will continue to be uninformed about the
NFIP, magnitude of flood hazards, and property protection alternatives, and will possibly pay
higher flood insurance premiums.
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
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TABLE 8-14.
FEMA COMMUNITY RATING SYSTEM ACTIVITIES
300
Public Information Activities
310
Elevation Certificates: Maintain FEMA elevation certificates on new buildings in
the floodplain and make copies available upon request.
320
Map Determinations: Respond to inquiries to determine what Flood Insurance Rate
map zone a property is in and publicize this service.
330
Outreach Projects: Send information about the flood hazard, flood insurance, and
flood protection measures to residents.
340
Hazard Disclosure: Ensure that potential purchasers of flood -prone property are
aware of the flood hazard through disclosure by real estate agents or deed records.
350
Flood Protection Library: The public library maintains and publicizes references on
flood insurance and flood protection.
360
Flood Protection Assistance: Give inquiring property owners technical advice on
how to protect their buildings from flooding and publicize this service.
400
Mapping and Regulatory Activities
410
Additional Flood Data: Develop new flood elevations, floodway delineations, etc.,
or have the flood insurance study based on higher standards.
420
Open Space Preservation: Guarantee that portions of currently vacant floodplain
will be kept free from development.
430
Higher Regulatory Standards: Adopt building and development regulations with
higher standards than the minimum NFIP requirements.
440
Flood Data Maintenance: Keep flood and property data on computer records or
better base maps, maintain elevation reference marks.
450
Stormwater Management: Require new developments throughout the watershed to
ensure that their stormwater runoff will be no greater than the runoff from the sites
before development.
500
Flood Damage Reduction Activities
510
Repetitive Loss Projects: Develop and implement a plan to reduce damage in
repeatedly flooded areas.
520
Acquisition and Relocation: Acquire or relocate flood -prone buildings so that they
are out of the floodplain.
530
Retrofitting: Document floodproofed or elevated pre -FIRM buildings.
540
Drainage System Maintenance: Conduct periodic inspections of all channels and
retention basins and remove debris as needed.
600
Flood Preparedness Activities
610
Flood Warning Program: Provide early warnings and have a detailed plan keyed to
flood crest predictions.
620
Levee Safety: Maintain levees that are not credited with providing base flood
protection.
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
630 Dam Safety: Credit dependent upon state dam safety program.
Preferred Alternative
To increase public education and reduce flood insurance premiums the following are
recommended:
• The County should hire a public education officer to manage a public education
and CRS program
• The County should immediately enroll in the CRS using a "short form"
(Appendix E of the Community Rating System Coordinator's Manual). The
purpose of the short form is to assist a jurisdiction with at least 500 credit points
to achieve a Class 9 rating quickly and realize immediate savings on policy
premiums. The full application containing additional details may be completed
at a later date to realize additional savings
• The County should submit the full set of required documentation to update its
CRS rating following adoption of the CFHMP. Full application will provide the
largest benefit when many of the structural and nonstructural recommendations
of the CFHMP have been implemented. Many of the CFHMP recommendations
would receive CRS credit.
The Community Rating System (CRS) is a program developed by FEMA to enable communities
in the National Flood Insurance Program (NFIP) to earn reductions in their flood insurance
rates. There are several broad categories of activities a community could do to reduce their
flood risks, and these earn them points. The number of points they earn puts them in a
category which drops the flood insurance premiums for everyone in their community. The
more points, the more the premiums are reduced.
Yakima County will be signing up for this program. The national director of CRS and our
regional representative will be in Washington State in September, and have offered to help us
fill out the extensive application packet. Having the unincorporated county in the program
first will allow us to gage the time and logistics required to be a participant. The Flood Control
Zone District will then talk with the cities that are part of the NFIP and help them join CRS, if
they would like. A side benefit besides the lower premiums will be a more focused and clear
tracking and documenting system for all things involving flood control and loss reduction.
RW15—Use of Geographic Information System (GIS) Data (27)
Problem Development
The County GIS system can be a valuable tool for flood hazard management, County planning,
and building permit review. GIS data can be used to identify parcels within the floodplain,
maintain an inventory of flood control works, and show elevation requirements for floodplain
development. However, the County has not yet achieved full integration of GIS into the
floodplain management, planning, and permitting processes.
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Discussion of Alternatives
GIS offers numerous applications that could support planning decisions and increase the
efficiency of permit reviews. The following GIS applications are examined as ways to improve
flood hazard management and permit reviews:
• Integrate digital FIRM and floodway maps from FEMA into the County's GIS.
• Create GIS coverages that include information on historical flood damage areas,
road closures, emergency transportation routes at various flood stages, and
accurate topographical data.
• Integrate GIS into the permit process by generating reports to be used for
pre -application conferences.
• Continually update the GIS parcel database to reflect annual rezones,
comprehensive plan amendments, and updates to critical flood hazard
information.
Digital Flood Insurance Rate Maps
FEMA is the agency responsible for creating, updating, and distributing Flood Insurance Rate
Map (FIRM) information to local governments and other private sector users. As the
development of GIS systems expanded during the 1980s, FEMA investigated the potential of
digital versions of traditional FIRMs. These would allow rapid reproduction of FIRMs, as well
as the distribution of flood hazard data contained within them to GIS systems throughout the
country. This allows the FIRM data to be used in conjunction with other data contained in a
jurisdiction's GIS to correlate the potential for flooding with other community variables.
Beginning in 1992, FEMA initiated a program to develop digital FIRMs that would accomplish
these purposes.
There are currently four distinct types of digital flood hazard data available from FEMA under
the DFIRM program (DFIRM, DFIRM-DLG, FIRM -DLG, and Q3 Flood Data). Each of these
types of data serves a distinct purpose, and is generated according to different specifications.
The choice of data to obtain and use depends wholly upon the task to be performed, and
extreme caution should be used in selecting the data format to use. The four data types are
summarized in Table 8-15.
Given the range of data being generated, it will be important for the County to define objectives
for the flood hazard data, and to design meaningful applications appropriate to the scale,
content, and quality of the data selected. The following objectives should be followed to
evaluate the selection and use of digital flood information.
• Accuracy: Establish definitive and accurate representations of the floodway, 100 -
year floodplain, Special Flood Hazard Areas (SFHAs), and Base Flood Elevations
(BFEs)
• Completeness: Ensure that all of the items listed above are present in the GIS
database and that the database includes all jurisdictions within Yakima County
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Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Accessibility: Enhance the County's ability to perform floodplain determinations,
measure areas of SFHAs, determine BFEs of specific locations, and realize time
savings in the permit process
• Community Review: Ensure that sufficient local review of flood hazard
information has occurred prior to release of that data for public use.
In order to achieve fully the objectives set forth, the County must continue to demand DFIRM
or FIRM -DLG data from FEMA, or must seek some process to generate the data internally
based on manuscript FIRMs (essentially creating its own version of a FIRM -DLG). Without the
advantages afforded by base flood elevation information, accurate placement of features, and
official record status, Q3 data are little more than a public information and flood insurance
marketing tool. While that may be entirely appropriate for response/recovery applications and
general planning use, when it comes to the review of a development proposal or rating of a
flood insurance policy, practitioners still must resort to manuscripts and documentation
because the federal government has not provided jurisdictions digital data of sufficient scale
and detail to accomplish these tasks. Until FEMA provides the County a DFIRM, DFIRM-DLG,
or FIRM -DLG, the objectives listed above cannot be met in whole, and the reliability of
conclusions reached using digital flood data must continue to be questioned.
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...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Additional Flood Hazard Data Development
In addition to flood hazard data from a FIRM or FIS, the County has the ability to assemble
additional GIS coverages that describe historical flood damage areas, road closures, emergency
transportation routes at various flood stages, and accurate topographical data.
Historical flood damage can be recorded based on preliminary damage assessments, individual
assistance applications, and damage survey reports conducted following floods declared
federal disasters. FEMA has begun compiling this information as point surveys using a GIS.
Each application or survey is geocoded as it is entered into the disaster application system,
allowing for creation of point coverages that maintain all attributes of the application or survey.
Similar coverages have also been created by researching past disasters and coding results in
order to measure repetitive damage. Privacy issues surround release of this data to the public
because some of the attributes of an application for disaster assistance, such as the name and
address of each applicant, violate privacy act regulations if they are released for use beyond
their direct purpose (the distribution of federal aid). However, once the data have been
geocoded and points created, any privacy -sensitive attributes can easily be dropped from the
attribute tables, creating a valuable indicator of the extent of a disaster that would be available
to the public. Collection and distribution of these data are still in an infancy stage. The County
should explore with FEMA the possibility of obtaining this information for use in the future.
The County Public Works Department also maintains a record of roads (by log number) closed
during major flood events. GIS was used to log these data during the February 1996 event. It
would benefit the County to create additional coverages to show damaged and closed roads
during each of the major historical floods analyzed in the CFHMP. Alternative emergency
routes should be defined for each affected road segment and added to the GIS. Trends over
time would also be useful in the creation of a database that catalogues which roads are affected
and should be closed at specific river stages on the mainstem or tributaries of the Yakima River.
The road closure database would be one of the most useful applications of flood hazard data
afforded by the GIS. For each road in each affected area, a range of flows observed in the
associated stream should be developed to dictate if a warning should be issued, which
alternative emergency routes should be activated, and if the road should be closed. These
thresholds (warning, emergency route activation, road closure) should then be integrated with
corresponding levels of response initiated by OEM during a flooding activity (warning, alert,
emergency). The EOC would be an appropriate place to maintain this GIS database.
Permit Process
EHSB 1724 (1995), a new regulatory reform law, streamlines local land use permitting, enhances
public notice, and establishes new procedures for judicial appeal of local land use decisions.
This law requires local governments to combine environmental review with their project permit
process and provide for no more than one open -record hearing and one closed -record appeal.
The law also requires that the County's shoreline master program be an element of the
comprehensive plan. Due to the limited number of hearings and appeals, as well as the
requirement to accomplish environmental and permit review concurrently, quick access to a
wide range of accurate information is vital to the successful completion of pre -application
8-97
The Flood Control Zone District is implementing all of the above recommendations plus much
more. In 2002, Congress tripled the funding available for floodplain mapping, and the FCZD
is planning on updating the majority of floodplain maps across the County over the next 5-6
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
hearings. If a local agency can supply the developer with detailed information on requirements
during this hearing, both parties may save time over the course of permit approval.
GIS can be used in a data -rich environment such as Yakima County to provide valuable data
for use in the permit process. The GIS could construct a pre -application report driven by the
parcel number, legal description, or general location of a proposed project. The report can be
constructed as a macro that queries all critical areas, zoning, and floodplain status, and returns
mitigation requirements sensitive to the location and desired use of the proposed project.
Zoning information should return permitted and conditional uses, as well as factors that may
force a variance from the Urban Area Zoning Ordinance and County Zoning Ordinance. Flood
information should include the SFHA designation and BFE of the site, and should provide a
listing of mitigation and absolute elevation requirements sensitive to the location and desired
use from the Critical Areas Ordinance. Additional mitigation requirements for steep slopes,
geologically hazardous areas, wetlands, and forest resource areas should also be queried and
listed in the report. The results may be output in report and map format and given to the
developer at the conference. Interpretation of actual project impact should still take place using
the professional discretion of the Planning Department, but the report provides a screening tool
that would be useful early in the permit review process.
Updates to GIS Information
The County should continue to update and review the contents of its GIS database as it is doing
now. System updates should occur after annual rezones and comprehensive plan amendments
following a release of new FIRM products, and after parcel boundary changes due to
subdivisions. Changes to information obtained from the County Assessor would be
automatically incorporated via an external link to the Assessor's database.
Preferred Alternative
To accomplish objectives for the use of GIS in day-to-day flood hazard management activity,
the County should perform the following actions:
• Obtain from FEMA the best available digital flood hazard map that meets the
objectives listed above
• Assemble GIS coverages documenting closed and damaged roads from historic
flood events discussed in the CFHMP. Analyze spatial trends relative to stream
stage levels to build relationships between flow rates and road closures
• Obtain flood damage GIS coverages for recent and historical floods as they
become available from FEMA. Observe privacy act requirements in reporting
this information
• Construct a GIS permit review tool, which will also substantially increase the
effectiveness of evaluating flood hazards over the long term
• Continue Standard GIS data updates.
8-98
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
years. One of the critical features of these updates is that the FEMA maps will be entirely
digital, and be on a County -wide basis (currently the maps are by jurisdiction) to provide
consistency and much easier map update throughout the County. In the process of map
revision we have or will acquire much better topographic data through the use of LIDAR (Light
Detection and Ranging) data, and generate more accurate hydraulic and hydrologic models,
which will also be placed on the GIS.
OSA1—Continued Flood Damage Outside the CFHMP Study Area (30)
Problem Definition
Damage from the earliest recorded floods was concentrated in the Mid -Valley area. Following
the construction of levees along the Yakima mainstem, damage became more concentrated in
the Lower Valley and along tributary streams. Ahtanum, Bachelor, Wide Hollow, Wenas,
Toppenish, and Satus Creeks repeatedly produce flood damage. The Yakima and Upper
Naches Rivers also encroach on homes and inundate roads in the communities of Toppenish,
Wapato, Parker, Buena, Naches, and Gleed.
Discussion of Alternatives
As revealed in the descriptions of historical floods (Chapter 4), over 80 percent of the flood
damage resulting from the February 1996 event occurred outside the CFHMP study area along
tributary creeks. To address flooding in these areas, additional planning needs to be
conducted. The CFHMP planning process, as described in Chapter 1, can be easily applied to
other drainage basins located throughout the County. Expanding planning to include
additional drainage basins would provide guidance to reduce flood hazards, correct poor
floodplain management practices, and guide further land use changes. If no action is taken,
flood damage will continue to occur.
Preferred Alternative
To address flood damage outside the study area, the following are recommended:
• The County should expand CFHMP planning to other areas of the County on a
watershed basis. Planning should be concentrated on high -damage areas such
as Ahtanum, Bachelor, Wide Hollow, and Wenas Creeks, and the Upper Naches
and Lower Valley. Planning should begin now by documenting flood issues
from historical floods and during future flood events
• The County should adopt the Comprehensive Stormwater Management Plan to
reduce localized flooding in the Yakima urban areas.
The Flood Control Zone District is in the process of beginning other CFHMP's
throughout the County. The Surface Water Management Division of Yakima County
Public Works is updating and implementing a Comprehensive Stormwater
Management Program for the Yakima Urbanized area in cooperation with the City of
Yakima and the City of Union Gap.
8-99
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
MR4 —Right Bank Yakima River Levee near Boise Cascade Pond (31), and
MR6—Flood Damage to Greenway Path near Boise Cascade Pond (37)
Problem Definition
A portion of a federal levee on the right bank of the Yakima River from Rotary Lake to
downstream of the Boise Cascade Pond fails to meet FEMA's freeboard standards. Portions of
the levee are currently used by the Yakima Greenway as a bike path. During the February 1996
flood, the pathway breached at several locations downstream of the R Street underpass near the
Boise Cascade Pond upstream of the trestles. This caused an estimated $72,000 in damage to
Yakima Greenway facilities. None of the levels in this reach overtopped or breached during
1996.
Discussion of Alternatives
To evaluate the potential for flood hazard reduction in this area, the following alternatives were
examined:
• Raise the existing pathway levee to FEMA's freeboard standards
• Relocate the pathway levee to an area with a lower potential for overtopping and
erosion
• Install culverts in the damaged pathway levee to minimize overtopping, and
construct an overflow channel
• Construct the pathway levee for overtopping by decreasing top elevation near
the breach areas and construct an overflow channel
• Rebuild the pathway levee using higher design standards
• Rebuild the pathway levee to pre -flood conditions.
Advantages and disadvantages of each alternative are summarized in Table 8-16. Many of the
alternatives are quite costly in comparison with the potential reduction in damage. Each
alternative provides a limited incremental increase in property protected or reduction in
potential flood damage. Reducing damage from that which occurred during the February 1996
flood (estimated at $72,000) may not justify the cost of many of the alternatives. For example,
does $679,000 to relocate the pathway levee justify the reduction of potential flood damage of
$72,000 during a 100 -year event?
Preferred Alternative
Based on the selection criteria described in Chapter 7, the selected alternative is to rebuild the
existing pathway levee using higher design standards This is the only alternative for which
potential benefits exceed costs. Potential public benefits associated with other alternatives do
not justify the additional cost. Therefore, the following are recommended:
• Rebuild the existing pathway levee to pre -flood conditions; however, install
additional embankment protection by applying heavy riprap in the highly
erosive areas. This was accomplished following the February 1996 flood.
• Establish a maintenance budget for Greenway facilities. Rebuilding to higher
design standards will reduce damage during smaller flood events, but damage
8-100
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
should be expected during large events due to the location of the facilities.
Establishing a maintenance budget would provide funds to repair facilities after
significant flood events.
No Change
LR6 — Spring Creek Backwater Flooding (33)
Problem Definition
Historically, Spring Creek conveyed Yakima mainstem floodwaters upstream of Union Gap.
Flooding along Spring Creek was reduced with the installation of a floodgate in 1985 near the
Valley Boulevard interchange, preventing Yakima floodwater from entering Spring Creek
during high flows on the Yakima River. However, during significant flood events, the Yakima
River rises to a level that inundates the southeastern portion of Union Gap, with floodwaters
near Union Gap extending into the Ahtanum Creek drainage. If high flow is also experienced
on Ahtanum Creek, the flooding can be aggravated. Floodwaters inundate residential and
public property located near the mouths of Spring, Wide Hollow, and Ahtanum Creeks. In this
area, flood damage has occurred to mobile homes and the City of Union Gap sanitary sewer
pump station.
8-101
MB 1 NM MR 111111 1 NS 11111 11111 11111 I EN MI En a 11111 MO
TABLE 8-16.
ALTERNATIVES FOR BOISE CASCADE LEVEE PATHWAY
Alternative
Planing Level
Cost Estimate
Advantages
Disadvantages
Raise the existing pathway levee
to FEMA's freeboard standards
Relocate the pathway levee to an
area that has lower flood damage
potential without repairing
existing levee
Install culverts within the
damaged pathway levee areas to
minimize overtopping potential
and construct overflow channel
Construct pathway levee for
overtopping by decreasing the
top elevation near the breach
areas and construct an overflow
channel
Rebuild the pathway levee to
pre -flood conditions with higher
design standards
Replace pathway levee to pre -
flood conditions
$620,000 • Provides additional flood protection
for Greenway Parks and I-82
$679,000 • Reduces potential for pathway
overtopping and eroding
• Opens additional floodplain area for
floodwater conveyance and storage
• Reduces pathway maintenance
$265,000 • Reduces potential for pathway
overtopping and eroding
• Opens additional floodplain area for
floodwater conveyance and storage
$223,000 • Reduces potential for pathway eroding
• Opens additional floodplain area for
floodwater conveyance and storage
$132,000 • Maintains flood protection to property
behind pathway
• Reduces potential for erosion
$72,000 • Maintains flood protection to property
behind pathway
• Limited incremental increase m property
protected
• I-82 currently acts as a standard levee to
limit spreading of floodwaters
• Eliminates floodplain storage and
conveyance area
• Requires additional County maintenance
• Cost
• Increased flood risk for property behind
existing pathway
• Pathway would be located closer to the
freeway
• Cost
• Increased flood risk for property behind
existing pathway
• Potential for debris jam
• Cost
• Increased flood risk for property behind
existing pathway
• Cost
• Continued maintenance and repair costs
• Reduces potential right overbank
floodplain storage and conveyance area
during small flood events
• Continued maintenance and repair costs
• Reduces potential right overbank
floodplain storage and conveyance area
during small flood events
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
Discussion of Alternatives
Southeastern Union Gap floods under the following conditions:
• The Yakima mainstem inundates areas near the mouths of Spring, Wide Hollow,
and Ahtanum Creek due to the floodplain topography
• Tributaries of the Yakima River (Ahtanum and Wide Hollow Creeks) experience
high flow, causing overbank flooding due to inadequate conveyance capacity
(HDR 1993)
• A combination of the two.
Significant structural modifications to the Yakima River floodplain would be required to reduce
or eliminate flooding in southeastern Union Gap during significant flood events on the Yakima
mainstem or during Yakima mainstem flooding combined with tributary flooding.
Floodwaters on the Yakima mainstem would need to be contained east of I-82; floodwaters on
Ahtanum Creek would need to be contained south of the railroad grade; Wide Hollow Creek
would require a high-flow diversion and a closure structure would need to be constructed near
the mouth of Wide Hollow Creek. This would potentially involve raising I-82, raising the
railroad grade, constructing a high-flow channel for Wide Hollow Creek, and constructing a
closure structure. The financial feasibility of this type of solution is highly unlikely given the
anticipated benefits. Therefore, it seems more appropriate to address only the flood damage
associated with tributary flooding and to prepare residents within the existing floodplain for
flooding during significant events.
The City of Yakima's draft Comprehensive Stormwater Management Plan (HDR 1993)
recommended a high water overflow channel within the Wide Hollow drainage to reduce flood
damage. The project would redirect high flows in Wide Hollow Creek away from the City of
Union Gap. A proposed diversion structure would pass low flows into the existing channel but
divert high flows to the south between the two existing railroad embankments. This project
would reduce flood damage when Wide Hollow Creek is experiencing high flow; however,
flooding is likely to continue when high water is also present on the Yakima mainstem.
As of April 25, 1996, FEMA had five requests for private disaster assistance in the southeastern
portion of Union Gap near the confluence of Wide Hollow Creek and Spring Creek
(Appendix B). The amount of damage is currently unknown. Many of the residents in this area
have experienced flood damage in the past and have taken precautionary measures by
floodproofing or purchasing flood insurance. However, additional floodproofing, such as
elevating, should be promoted to residents in this area who continue to experience flood
damage. Floodproofing is also appropriate for the City of Union Gap's pump station in this
area. Elevating the electrical panel or building a flood wall to prevent floodwater from entering
the pump station could reduce damage at this public facility.
Preferred Alternative
To address flood damage within southeastern Union Gap, the following are recommended:
• Integrate floodproofing techniques into the City of Union Gap's pump station
8-103
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Promote floodproofing and flood insurance to Union Gap residents who
experienced damaged during the February 1996 flood
• Construct the Wide Hollow Creek high-flow bypass as recommended in the
draft Comprehensive Stormwater Management Plan, with the knowledge that
severe flooding on the Yakima mainstem will continue to flood this area. Prior
to final design, maximum flow through the low -flow channel should be
determined using the Yakima River flood stage as a boundary condition and
integrating considerations for a temporary closure structure near the mouth of
the low -flow channel
• Conduct a comprehensive drainage study for the Ahtanum Creek watershed as
recommended in issue OSA1 —Continued Flood Damage Outside the CFHMP
Study Area.
The issues here have been previously addressed in item LR3, increased Flood Elevation
Near Union Gap. The remainders of these issues are better addressed in the
forthcoming Ahtanum/Wide Hollow CFHMP which will take a much more in-depth
look at these problems and their relationships to each other.
MR3—KOA Campground Levee (34)
Problem Definition
The KOA levee is located along the left bank of the Yakima River directly upstream of the SR 24
bridge and protects downstream residents. Diking District No. 1 recently upgraded the levee to
FEMA standards and obtained 100 -year levee certification from the COE. FEMA floodplain
maps are currently being modified to incorporate this flood -control structure. However, the
levee did experience some damage during the February 1996 flood: embankment rock was
eroded for approximately 50 feet.
Discussion of Alternatives
The KOA levee performed well during the February 1996 flood event. Minimal damage was
experienced given the severity of the flood event and location of the levee. The levee is located
in a constricted area on the outside bend of the river; therefore, the levee experiences significant
erosive forces during high flow. Diking District No. 1 installed spur dikes to decrease the
erosive forces, and they performed well during the February event. At this time no additional
modifications to the levee seems appropriate. The COE is pursuing the repair of this levee to
pre -flood conditions.
Preferred Alternative
Based on the performance of the KOA levee during the February 1996 event, the following is
recommended:
• Strengthen the damaged section of levee by adding additional riprap as needed.
Inspect spur dike during low flow and repair as needed. (Diking District No. 1
has taken action to solve this problem).
8-104
...CHAPTER 8. DRAFT ANALYSIS OF FLOOD HAZARD MANAGEMENT ALTERNATIVES
See also LR5. The damage to the KOA levee is directly related to its location relative to
SR 24 and the other levees. Reconfiguration of this levee will render this problem
moot.
MR7—Flood Damage to Robertson Landing (35), and
UR3 — Flood Damage to Harlan Landing (38), and
UR4 — Inundation of Elks Golf Course (39)
Problem Definition
Robertson Landing is located along the right bank of the Yakima River just upstream of the
SR 24 bridge; Harlan Landing is on the left bank just upstream of the mouth of the Naches
River. Flooding occurs frequently at these sites due to their location, resulting in loss of boat
ramps and picnic areas, deposit of sediment in parking areas, and damage to pathways.
The Elks Golf Course is adjacent to the Yakima River directly upstream of Selah Gap; portions
of the course are in the Yakima River floodway. Flooding occurs frequently here as well due to
the location, causing sediment deposition and localized erosion throughout the golf course.
Discussion of Alternatives
Within the floodplain, recreational land use is preferable to urban development to limit
potential flood damage. However, it should be understood that some flood damage will
continue given the location of the facilities. A portion of the golf course and numerous
Greenway facilities are located in the Yakima River floodway. Therefore, they will be subject to
repetitive flooding and erosive action of floodwaters. Short of removing the facilities from the
floodway, the only alternatives to reduce flood damage would be to use higher pathway design
standards, remove temporary structures (e.g., picnic tables and trash cans) prior to impending
floods, floodproof permanent structures (e.g., vaulted bathrooms and golf course structures),
and monitor development so that flooding conditions do not become worse in the future.
Preferred Alternative
The following are recommended to minimize damage to Greenway and Elks Golf Course
facilities:
• Floodproof repetitively damaged structures by moving them to a higher
elevation or installing flood walls or sealant
• Rebuild Greenway pathways to higher design standards such as using more
erosion -resistant embankment protection
• Establish a maintenance budget to provide funding for the repair of inevitable
future flood damage to roadways, pathways, and the Elks Golf Course
• Establish flood response teams to remove temporary structures prior to a
impending flood event
• Educate Greenway users about flooding by installing interpretive signs near
damaged sites that describe floodplains, floodways, effective floodplain
management, and how various actions can aggravate flooding and flood damage
8-105
Draft Upper Yakima River Comprehensive Flood Hazard Management Plan Amendment.
• Continually monitor cumulative effects of development in the area to limit the
potential of aggravating flood damage.
No Change.
8-106
OM MO MN MI MIMI IIIIIII 11111 MIN SIMI INN OM =I MINI MIN OM NM NMI INN IMO
Legend
POW@ Lite PM'Olt
AIR TERMINAL
CITY
COuNTY
COUNTWOITY
EziDEPT OF INTERIOR
MI SEWER DIST
1 IRRIOATION DIST
STATE
STATE . DOT
3 STATE - PARKS
f STATE DEPT OP GAME
7\v/ Roads
igg Riven
Preliminary Revised Ploodpiain Boundaries
, - 100.year Floociplain
Floodway
C:I Study Area
1 0 1 2 Mlles
/0/7 Pint Avenue
Seattle, VtfaVlington 98107
Yakima County
UPPER YAKIMA RIVER CFHMP
Figure 8-8.
PUBLIC USE PARCELS
M NM- NM N-- 8 r I- - M-- - N U 111111
MoCuiiou ►t1 Road
LEGEND
Section Lines
Quarter -Section Linea
2104-1D Section -Township -Range Number
▪ February Flood Damaged Structures
Identified by inspection
Number of Structures in the Floodplain
Within the Quarter -Section;
▪ Residential
fJ Commercial
A Agricultural
0 2,000' 4,000' 8,000' 0,000' 10,000'
KCM
7917 First Avenue
Seattle, Washington 98101
Yakima County
UPPER YAKIMA RIVER CFHMP
Figure 8-7.
IDENTIFIED STRUCTURES IN THE FLOODPLAIN
= IIIIII M I = I I = NM NE NM
Legend
fli4 Issue Location
Rivers
4.Roads
e irninary Revised Floodplain Boundaries
100 -year Floodplain
Floodway
CFNMP Study Area
0
116p511■Wine Flooding Issue
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e —�+-i 00 _ _
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flood PAMA;rs Co Roberto Wang
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d
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1,42
Protection of Pr4vAte Property
L111
inctaaaai flood Rievati.n
;114
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additional rla,.od Protaction baloW
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Issues not shown on trap:
2
N
3 Mlles
K M
1917 First Avenue
Seattle, Washington 98101
Yakima County
UPPER YAKIMA RIVER CFHMP
Figure 8-1.
IDENTIFIED FLOODING ISSUES
IMO NMI NIS INN NS 1E11 IMO III MO MO IMO 1E11 1111 ENO UII EIS UM IMO
8
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Legend
Existing FEMA Floodplain
cp Predicted Actual Floodplain (with existing levee)
Nagulatory FloodpItain UnChanged from FEMA Floodplain
=I Predicted Regutatery Flebdpleirl (with 100-yeer setback levee)
cf Predicted Regulatory Floodplein (vmth 2,000'100 -year levee)
Preateten Reptilittry Floodplain (wfth 10,000' i00-yeer levee)
Text Cress -Section ID
C&S-Section
Yakima River
LV Roadways
Pelee! Aecessed Values
No Bog Improverhehte
$1 - $25,000
525,001 S50,000
$50,001 $75,000
$75,001 - $100,000
Eas $100,001. $500,000
1111 $600,001 $1 million
si makon - $5 minion
is $5 million .$510 Minton
21500
21400
21350
21300
21250
eti'e R
0.6
0
0.6
1.2 Mites
KC
15,17 First Avenue
Seattle, Washington 98101
Yakima County
UPPER YAKIMA RIVER CFHMP
Figure 8-2.
ASSESSED VALUE PROTECTED
BY LEVEE ALTERNATIVES