2007 Upper Yakima River Update

Covers

  1. Front Cover (PDF)
  2. Inside Cover (PDF)
Title
Page Number
Acknowledgments (PDF)
 i
Table of Contents (This Page)
 ii
List of Tables
 vii
List of Figures
 ix
List of Abbreviations
 xi
Executive Summary
 ES-1
Comprehensive Flood Hazard Management Planning
 ES-2
1998 Upper Yakima CFHMP
 ES-3
CFHMP Goals and Objectives ES-3
2007 Upper Yakima CFHMP Update
 ES-5
Recommended Actions
 ES-7
Project Implementation Strategy
 ES-13
1. Introduction (PDF)
 1-1
Background
 1-1
Flooding Issues in Study Area
 1-1
Principles of Flood Hazard Management
 1-2
Authority and Scope for Yakima County CFHMP
 1-2
Plan Development Process
 1-4
Involving the Public and Affected Agencies
 1-4
Defining Goals and Objectives
 1-8
Collecting Data
 1-8
Related Programs or Actions
 1-11
Plan 2015 - Yakima Countys Comprehensive Plan
 1-11
Yakima County Revised Flood Insurance Study
 1-11
Flood Control Assistance Account Program
 1-11
Funding
 1-12
Requirements for CFHMPs
 1-12
Applicant Eligibility
 1-13
Maintenance Project Eligibility
 1-13
Emergency Projects
 1-14
Required Consultation with Other Agencies
 1-14
2. Study Area Characteristics (PDF)
 2-1
Yakima River Basin
 2-1
Study Area Limits
 2-2
Upper Reach - Yakima Canyon to Selah Gap
 2-2
Middle Reach - Selah Gap to SR 24 Bridge
 2-4
Lower Reach - SR 24 Bridge to Union Gap
 2-5
Physical Characteristics
 2-5
Climate
 2-5
Hydrology
 2-5
Geology
 2-8
Soils
 2-10
Wetlands
 2-11
Fisheries and Wildlife
 2-11
Vegetation
 2-12
Water Quality
 2-13
Socioeconomic Characteristics
 2-15
Jurisdictional Boundaries
 2-15
Population
 2-15
Land Use
 2-16
3. Previous Studies (PDF)
 3-2
Revised Preliminary Yakima County Flood Insurance Study
 3-2
Estimated Flood Flows
 3-2
Hydraulic Computer Modeling
 3-7
Flood Insurance Rate Maps, Floodway Maps, and Flood Boundary Maps
 3-8
1970 Floodplain Information; Yakima and Naches Rivers
 3-9
1973 Floodplain Information; City of Selah and Vicinity
 3-9
1978 Yakima-Union Gap Flood Damage Reduction Report
 3-10
Alternative 1 - No Action
 3-10
Alternative 2 - Floodplain Management Alone
 3-10
Alternative 3 - Floodplain Management with Additional Flood
Control Storage
3-10
Alternative 4 - Floodplain Management with Levees
 3-12
Alternative 5 - Floodplain Management with Channel Modification
 3-12
Alternative 6 - Purchase of Development Rights
 3-12
Alternative 7 - Purchase of Floodway
 3-12
Recommended Plan
 3-13
1986 Yakima-Union Gap Flood Control Project
 3-14
1991 Yakima River Flood Evaluation for Yakima County Diking District No. 1
 3-14
Estimated Flood Flows
 3-15
Review of Historical Floods
 3-15
Issues Identified as Affecting Flood Risks
 3-16
Assessment of Previous Studies
 3-16
Key Results from Previous Studies
 3-17
Recent Related Studies
 3-18
1998 Department of Natural Resources Flood Plains, Salmon Habitat,
and Sand and Gravel Mining
3-19
1998 Department of Natural Resources Reclamation of
Flood-Plain Sand and Gravel Pits and Off-Channel Salmon Habitat
3-19
1998 Revisions to Yakima County Flood Insurance Study
 3-19
Yakima River Floodplain Mining Impact Study (2002)
 3-19
The Reaches Project Report (2002)
 3-21
SR 24 Project Floodplain Consistency Report (2003)
 3-23
Lower Naches River Coordination Project (2005)
 3-23
Yakima County Mineral Resource Task Force (2006)
 3-26
Conclusions - Additional Ongoing Efforts that Affect Flood Management
 3-27
2003 Yakima River Basin Water Storage Feasibility Study
 3-28
Subbasin Plan and Salmon Recovery
 3-28
4. Yakima River Flooding Characteristics (PDF)
 4-1
Common Flood Characteristics
 4-1
Flood Magnitude
 4-1
Flood Duration
 4-2
Channel Migration
 4-3
Sediment Transport and Deposition
 4-4
Effects of Levees
 4-8
Effects of Roads and Bridges
 4-8
Effects of Reservoir Storage
 4-9
Flood History
 4-9
February 9, 1996, Flood
 4-10
November 30, 1995, Flood
 4-14
February 1995 Floods
 4-14
November 26, 1990, Flood
 4-15
December 27, 1980, Flood
 4-18
December 2, 1977, Flood
 4-18
December 4, 1975, Flood
 4-19
January 16, 1974, Flood
 4-19
March 14, 1972, Flood
 4-20
May 29, 1948, Flood
 4-20
December 23, 1933, Flood
 4-21
Summary of Historical Floods
 4-21
Historical Flood Improvement Projects
 4-22
5. Flood Control Facilities and Programs (PDF)
 5-1
Facilities Inventory
 5-1
Yakima Levee Project
 5-1
Public Law 84-99 Levees
 5-2
Highways
 5-4
Other Flood Control Works
 5-6
Operation and Maintenance
 5-11
Special Districts
 5-11
Other Flood-Related Programs
 5-11
United States Bureau of Reclamation, Yakima Project
 5-12
Yakima Greenway Foundation
 5-13
Yakima River Watershed Council
 5-20
Yakima River Basin Water Enhancement Project
 5-20
Yakima Subbasin Fish and Wildlife Planning Board (YSPB)
 5-21
Yakima Basin Salmon Recovery Board Lead Entity
 5-21
Yakima Basin Fish & Wildlife Recovery Board
 5-21
6. Regulations (PDF)
 6-1
Summary of Existing Regulations
 6-1
County Regulatory Tools for Flood Hazard Management
 6-8
City of Yakima
 6-11
City of Union Gap
 6-11
City of Selah
 6-12
NPDES Phase II Municipal Stormwater Permits
 6-13
Permitting Requirements
 6-14
SEPA/GMA Integration
 6-14
7. Alternative Analysis Approach (PDF)
 7-1
Flooding Issue Identification
 7-1
Flood Hazard Management Options
 7-1
Nonstructural Measures
 7-1
Structural Measures
 7-3
Alternative Analysis and Selection
 7-4
Considerations for Evaluating Alternatives
 7-4
Alternative Selection
 7-7
8. Analysis of Flood Mitigation Alternatives (PDF)
 8-1
LR5 - Aggradation/Reduced Flood Capacity Upstream of SR 24 Bridge;
Flood Damage to SR 24 Bridge, Yakima Regional Wastewater Treatment
Plant Levee, and DID #1 Levee (1)

8-3
MR2 - Yakima Beech Street Gravel Pit Levee (2), and
UR5 - East Selah Gravel Pit Levee (24)
8-25
LR3 - Increased Flood Elevation near Union Gap (3)
 8-30
LR7 - Capture of Edler Ponds (4)
 8-37
RW1 - Floodplain Mapping (5)
 8-38
RW20 - Loss of Channel Capacity due to Sediment Accumulation (6)
 8-42
NA1 - Bedload Movement and Channel Instability of Naches River (7)
 8-43
RW13 - Funding for Flood Control Work and Restoration Projects (8)
 8-44
RW6 - Public Disclosure of Floodplain Status (9)
 8-45
RW12 - Protection of State and County Roads (10)
 8-46
RW3 - Channel Migration (11), LR1 - Erosion of Agricultural Lands (15), and
UR1 - Erosion of Agricultural Land (22)
8-49
RW9 - Diversity of Opinions Relating to River Management (12), and
RW8 - County Policy on Flood Hazard Management (17)
8-50
RW4 - Flood Hazard Ordinance (13), and
RW5 - Revision and Consistency of Critical Areas Ordinance (25)
8-51
RW2 - Loss of Fisheries Habitat and Riparian Areas (14), and
MR8 - Borrow Pit Levee Upstream of Terrace Heights Bridge (31)
8-61
RW17 - Existing Structures in the Floodplain (16)
 8-64
RW16 - Operation and Maintenance of Flood Control Facilities (18)
 8-67
RW10 - Acquisition/Preservation of Floodplain Open Space (19)
 8-70
RW19 - Flood Warning and Emergency Response (20)
 8-73
RW18 - Community Rating System (21), and
RW7 - Flood Insurance and Public Education (28)
8-79
RW15 - Use of Geographic Information (GIS) Data (23)
 8-84
OSA1 - Continued Flood Damage Outside the CFHMP Study Area (26)
 8-88
MR6 - Flood Damage to Greenway path Near Boise Cascade Pond (32)
 8-89
LR6 - Spring Creek Backwater Flooding (29)
 8-92
MR7 - Flood Damage to Robertson Landing (30), UR3 - Flood Damage
to Harlan Landing (33), and UR4 - Inundation of Elks Golf Course (34)
8-94
9. Funding Options (PDF)
 9-1
Funding Sources
 9-2
County Administrative Options
 9-2
External Funding Sources
 9-10
Funding Source Evaluation
 9-23
Evaluation Criteria
 9-23
Programs to be Funded
 9-24
Large Project Funding Strategy
 9-27
References (PDF)
 R-1