Best Available Science

VOLUME I A REVIEW OF SCIENCE LITERATURE

KING COUNTY EXECUTIVE REPORT February 2004

Critical Areas, Stormwater, and Clearing and Grading Proposed Ordinances

Department of Natural Resources and Parks Department of Development and Environmental Services Department of Transportation Best Available Science

VOLUME I A REVIEW OF SCIENCE LITERATURE

KING COUNTY EXECUTIVE REPORT February 2004

Critical Areas, Stormwater, and Clearing and Grading Proposed Ordinances

Department of Natural Resources and Parks Water and Land Resources Division 201 South Jackson Street, Suite 600 Seattle, WA 98104 206-296-6519 TTY Relay: 711 dnr.metrokc.gov/wlr

Department of Development and Environmental Services Department of Transportation

Printed on recycled paper Alternate Formats Available 206-296-6519 TTY Relay: 711

Graphics Files: WLRNT8/CART/FINISHED/WORKGROUPS/Science/0401_BASreport/0401_BAStitle1.ai lpre EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume I – FEBRUARY 2004

King County Executive Ron Sims

King County Council Carolyn Edmonds District 1 Dow Constantine District 8 Bob Ferguson District 2 Steve Hammond District 9 Kathy Lambert District 3 Larry Gossett District 10 Larry Phillips District 4 Jane Hague District 11 Dwight Pelz District 5 David Irons District 12 Rob McKenna District 6 Julia Patterson District 13 Pete von Reichbauer District 7

Critical Areas Ordinance Policy Group: Stephanie Warden Director, Department of Development and Environmental Services Wally Archuleta Managing Engineer, Environmental Services Unit, Road Services Division, Department of Transportation John Briggs Deputy Prosecutor, Prosecuting Attorney’s Office Linda Dougherty Division Director, Roads Services Division, Department of Transportation Daryl Grigsby Division Director, Water and Land Resources Division, Department of Natural Resources and Parks Mark Isaacson Assistant Director, Water and Land Resources Division, Department of Natural Resources and Parks Joe Miles Division Director, Land Use Services Division, Department of Development and Environmental Services

CAO Project Management: Department of Development and Environmental Services: Lisa Pringle Project Manager, Barbara Heavey Code Project Lead Harry Reinert Policy Lead, DDES Roads Services Division (RSD), Department of Transportation: Howard Haemmerle Code Project Lead Water and Land Resources Division, Department of Natural Resources and Parks: Mary Jorgensen Best Available Science Project Lead Susan Oxholm Public Outreach Project Lead Richard Tucker Policy Lead

Principal Authors for Best Available Science Reports, Volume I & II, and Critical Areas Ordinance Code Development

Water and Land Resources Division, Department of Natural Resources and Parks: Stephanie Brown Critical Aquifer Recharge Areas Terry Butler, P.E., L.G. Channel Migration Zones Robert Fuerstenberg, Ph.D. Scientific Framework, Agricultural Effects (contributor to Aquatic Areas) Priscilla Kaufmann Flood Hazard Areas Gino Lucchetti Aquatic Areas Klaus Richter, Ph.D. Wetlands; contributor to Wildlife Areas Jeanne Stypula, P.E. Flood Hazard Areas Jennifer Vanderhoof Wildlife Areas

Environmental Unit, Roads Services Division (RSD), Department of Transportation: James Hatch, PG Geologic Hazard Areas

Principal CAO Project Staff

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EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume I – FEBRUARY 2004

Water and Land Resources Division, Department of Natural Resources and Parks: Claire Dyckman Code Development Lead for Review/ Reports and Mitigation Steve Foley Stormwater Project Lead Eric Maia Public Outreach Jill Moe Policy Lead Sarah Ogier Code Development Lead for Critical Aquifer Recharge Areas

Functional Managers: Roads Services Division (RSD), Department of Transportation: Ronda Strauch Supervising Engineer, Environmental Unit Water and Land Resources Division, Department of Natural Resources and Parks: Jerry Balcom Section Manager, Office of Rural and Resource Programs Dave Clark Manager, Flood Hazard Reduction Services Curt Crawford Managing Engineer, Stormwater Services Kate O’Laughlin Supervising Environmental Scientist, Watershed & Ecological Assessment Joanna Richey Section Manager, Strategic Initiatives Jim Simmonds Supervisor, Water Quality/ Water Quantity Group

Additional King County Participants: Department of Development and Environmental Services (DDES): Steve Bottheim Code Development Tony Cooper GIS Analyst Laura Casey Review – BAS and Code Jim Chan Review Don Gauthier Flood Hazard and Channel Migration Code Development Todd Hurley, P.G., Review – BAS, Geological Hazards Bill Kerschke Wildlife Areas Code Development Paul McCombs GIS Analyst Randy Sandin Code Development Karen Wolf Review

Department of Natural Resources and Parks Tom Bean Flood Hazard Code Development Bruce Bennett CARA Code Development John Bethel Geologic Hazard Areas Review Steven Burke Review Laurie Clinton Agricultural Code Sarah Coughlin Risk Assessment (no longer with King County) Maureen Dahlstrom Administration/ Public Outreach Tom Fox CARA Code Development Wendy Gable Collins Graphic Designer and Cartographer Collene Gaolach GIS Analyst Judy Herring Review Ken Johnson CARA Review and Code Todd Klinka GIS Coodinator Deborah Lester Risk Assessment Review Eric K. Nelson Agricultural Code Jo Merrick Administration/ Public Outreach Dave Monthie CARA Code Laurel Preston Graphic Designer and Cartographer Ken Rauscher GIS Analyst Rick Reinlasoder Review Deborah Snyder Code Review for Natural Resource Lands and Noxious Weeds Units Ted Sullivan Public Benefit Rating System Jennifer Thomas BAS (no longer with King County)

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EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume I – FEBRUARY 2004

Tom Ventur Graphic Designer Elizabeth Weldin Review, Agricultural Drainage Assistance Manager

Road Services Division, Department of Transportation Janel London Review: Flood Hazard Areas, CARA, and Channel Migration Zones Joseph Mathieu Review: Flood Hazard Areas and Channel Migration Zones Alan Momohara Review for Technical Support Unit of Roads Maintenance Erin Nelson Review: Geologic Hazard Areas Mike O’Neil Review Erick Thompson Review: Aquatic Areas and Wetland Areas

King County CAO Stakeholders Advisory Group:

Randy Bannecker Seattle King Association of Realtors Joan Burlingame Unincorporated King County Resident (Ravensdale) Dan Drais and Matt Mega Seattle Audubon Society Dan Chasan Unincorporated King County Resident (Vashon-Maury Island) Bill Harper Patterson Creek Flood Control Zone District Bob Johns King & Snohomish County Master Builders Association Bill Knutsen King County Agriculture Committee Ken Konigsmark King County Forest Advisory Committee Dyanne Sheldon Sheldon & Associates Bob Tidball Unincorporated King County Farmer (Auburn) Tim Trahimovich 1000 Friends of Washington Bill Woods King County Forest Advisory Committee

Best Available Science Reports Peer Reviewers: Paul Adamus, Ph.D. Adamus Resource Assessment, Inc., Corvalis, OR Lee Benda, Ph.D. Private Consultant, Mt. Shasta, CA Robert Brooks, PhD. Professor, Penn State University, Forest Resource Laboratory Mark Carey Branch Chief, Federal Insurance and Mitigation Division, FEMA, Bothell, WA. Dave Carlton, P.E. Federal Emergency Management Act, Bothell, WA. Stephen Conroy, Ph.D. Environmental Scientist III, King County, Seattle, WA Charles T. Ellingson, Principal Hydrologist, Pacific Groundwater Group, Seattle, WA. Correigh Greene, Ph.D. NRC Postdoctoral Research Associate, Watershed Program, Northwest Fisheries Science Center, Seattle, WA Douglas J. Kelly, PG, P.HG Hydrogeologist, Island County Environmental Health, Coupeville, WA Charles Lie, LEG, LHG Terra Associates, Inc, Goldbar, Washington Keith Macdonald, PhD. Private Consultant – Oceanography, Bellevue, WA John Marzluff, Ph.D. Associate Professor, College of Forest Resources, University of Washington, Seattle, WA Chris May, Ph.D. Private Consultant, Poulsbo, WA Sky Miller, P.E. Water Resources Engineer, Entranco, Bellevue, WA. David R. Montgomery, Ph.D. Professor, Department of Geological Sciences, University of Washington, Seattle, WA Laurie Morgan, PG, P.HG Hydrogeologist, Washington State Department of Ecology Michael Pollock, Ph.D. Ecosystems Analyst, Watershed Program, Northwest Fisheries Science Center, Seattle, WA Cygnia F. Rapp Shorelands and Environmental Assistance Program, WSDOE Phil Roni, Ph.D. Watershed Program Manager, National Marine Fisheries Service, Seattle, WA Chuck Steele State Floodplain Coordinator, WSDOE, Bellevue, WA.

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EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume I – FEBRUARY 2004

TABLE OF CONTENTS

CHAPTER 1 – INTRODUCTION 1.1 INTRODUCTION...... 1-1 1.1.1 Purpose and Background...... 1-1 Background ...... 1-2 1.1.2 Overview of WAC 365-195-905 to 925...... 1-2 King County’s Approach to Best Available Science ...... 1-4 1.2 CONTEXT ...... 1-4 Overview of Laws, Policies, and Programs for Resource Conservation ...... 1-5 Landscape and Population Overview...... 1-7 1.3 REVIEW OF CONTENTS ...... 1-8 1.4 REFERENCES...... 1-9

CHAPTER 2 – SCIENTIFIC FRAMEWORK 2.1 INTRODUCTION...... 2-1 2.2 LANDSCAPE EFFECTS...... 2-3 2.3 CONCLUSION ...... 2-5 2.4 REFERENCES...... 2-5

CHAPTER 3 – FLOOD HAZARD AREAS 3.1 INTRODUCTION...... 3-1 3.2 REVIEW OF LITERATURE...... 3-1 3.2.1 Description of Flood Hazard Areas...... 3-1 King County Rivers and Streams...... 3-1 Flood Hazard Areas: Delineation and Purpose ...... 3-2 3.2.2 FEMA and the NFIP ...... 3-2 3.2.3 Flood Hazard Area Functions...... 3-3 Natural Floodplains...... 3-3 Floodplain Alterations and Impacts ...... 3-4 3.2.4 Flood Hazard Area Protection...... 3-4 Flood Hazard Mapping and Regulation ...... 3-4 Contemporary Floodplain Management Policy and Regulations ...... 3-7 Impacts of Traditional Flood Control Facilities...... 3-7 Contemporary Design and Construction Guidelines for Flood Protection Projects...... 3-8

EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume I – FEBRUARY 2004

Comprehensive Floodplain Management Plans...... 3-9 3.2.5 Gaps in the Knowledge and Areas of Uncertainty...... 3-9 3.3 CONCLUSION ...... 3-10 3.4 LITERATURE REFERENCES ...... 3-11

CHAPTER 4 – CHANNEL MIGRATION ZONES 4.1 INTRODUCTION...... 4-1 4.2 REVIEW OF LITERATURE...... 4-1 4.2.1 Channel Migration Physical Processes ...... 4-2 Channel Migration Overview...... 4-2 Types of Channel Movement ...... 4-3 Some Natural Factors that Influence Channel Migration...... 4-5 Channel Migration, Floodplains, and Habitat ...... 4-6 4.2.2 Mapping Channel Change...... 4-7 4.2.3 CMZ Definition and Delineation ...... 4-7 4.3 SUMMARY AND CONCLUSION...... 4-9 4.5 REFERENCES...... 4-10 CHAPTER 5 – GEOLOGIC HAZARD AREAS 5.1 INTRODUCTION...... 5-1 5.2 REVIEW OF LITERATURE...... 5-1 5.2.1 Seismic Hazard Areas ...... 5-1 Seismic Hazard Area Functions ...... 5-2 Subsidence and Uplift ...... 5-4 Ground Failure ...... 5-4 Landslides...... 5-5 Liquefaction ...... 5-6 Differential Compaction...... 5-7 Water Waves ...... 5-7 Seismic Hazard Area Protection ...... 5-8 5.2.2 Erosion Hazard Areas...... 5-8 Erosion Hazard Area Functions ...... 5-10 Erosion Hazard Area Protection...... 5-10 5.2.3 Landslide Hazard Areas ...... 5-11 Landslide Hazard Area Functions ...... 5-12 5.2.4 Volcanic Hazard Areas...... 5-14 Volcanic Hazard Area Functions ...... 5-15

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5.2.5 Coal Mine Hazard Areas ...... 5-19 Coal Mine Hazard Area Functions...... 5-19 Coal Mine Hazard Area Protection ...... 5-22 5.3 CONCLUSION ...... 5-22 5.3 LITERATURE REFERENCES ...... 5-22

CHAPTER 6 – CRITICAL AQUIFER RECHARGE AREAS 6.1 INTRODUCTION...... 6-1 6.2 REVIEW OF LITERATURE...... 6-1 6.2.1 Definition of Aquifer Recharge Areas ...... 6-1 6.2.2 Prioritizing Aquifer Recharge Areas (Which are Most Critical?)...... 6-2 6.2.3 Identification and Assessment of Threatening Land-Use Activities...... 6-6 Water Quality ...... 6-6 Water Quantity ...... 6-19 Monitoring...... 6-21 6.2.3 Special Areas / Issues of Concern Specific to King County...... 6-23 6.3 CONCLUSION ...... 6-24 6.4 LITERATURE REFERENCES ...... 6-25

CHAPTER 7 – AQUATIC AREAS 7.1 INTRODUCTION...... 7-1 7.2 REVIEW OF LITERATURE...... 7-2 7.2.1 Processes that Form and Sustain Aquatic Areas and Species ...... 7-2 The Role of Water...... 7-2 The Role of Glaciers ...... 7-3 The Role of Forests ...... 7-3 The Role of Animals ...... 7-4 7.2.2 Natural Cycles of Change and the Role of Disturbance...... 7-5 Channel Migration and Shoreline Erosion...... 7-5 7.2.3 The Diversity of King County’s Aquatic Life ...... 7-6 Salmonids as Ecological Indicators and Keystone Species ...... 7-6 Other Species as Indicators of Ecological Health and Change ...... 7-8 7.2.4 Examples of Integrated Ecological Models: The River Continuum Concept and Marine Intertidal Zonation ...... 7-9 7.2.5 Effects of Land Development on Aquatic Habitats and Species ...... 7-13 7.2.6 Processes Conclusion...... 7-14 7.2.7 Strategies for Protection...... 7-15

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7.2.8 Approaches to Aquatic Area Protection...... 7-16 Riparian Areas...... 7-17 Protecting Landscape Scale Functions...... 7-26 7.2.9 Strategies for Protection Conclusion...... 7-27 7.3 LITERATURE REFERENCES ...... 7-28

CHAPTER 8 – WILDLIFE AREAS 8.1 INTRODUCTION...... 8-1 8.2 REVIEW OF LITERATURE...... 8-1 8.2.1 Conservation Theory...... 8-2 Landscapes, Ecosystems, and Populations...... 8-2 Ecosystem-Based Adaptive Management...... 8-3 Contemporary Ecology and the Implications for Conservation...... 8-3 8.2.2 Wildlife Areas Functions ...... 8-5 Human Dominated Landscapes and Variation of Functions Over Time ...... 8-5 Wildlife Areas Protection...... 8-7 Existing Habitat and Wildlife Protection ...... 8-7 Protection Suggested by Literature ...... 8-8 8.2.3 Protecting Individual Wildlife Species ...... 8-14 Spotted Owl...... 8-15 Peregrine Falcon...... 8-16 Vaux’s Swift...... 8-17 Marbled Murrelet ...... 8-18 Townsend’s Big-Eared Bat ...... 8-19 Osprey ...... 8-21 Northern Goshawk ...... 8-23 Great Blue Heron ...... 8-25 Bald Eagle ...... 8-26 Red-tailed Hawk...... 8-28 Remaining “Shall” Species ...... 8-31 “Should” Species...... 8-31 8.2.4 Priority Habitats...... 8-39 Caves ...... 8-39 Cliffs...... 8-41 Talus...... 8-42 Snags ...... 8-43

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Old-Growth and Mature Forest...... 8-45 Wildlife Corridors ...... 8-46 8.3 Conclusion...... 8-48 8.4 LITERATURE REFERENCES ...... 8-49

CHAPTER 9 – WETLANDS 9.1 INTRODUCTION...... 9-1 9.2 REVIEW OF LITERATURE...... 9-1 9.2.1 Wetland Definitions and Types...... 9-1 9.2.2 Wetland Functions...... 9-3 Determinants of Function...... 9-3 Interaction of Wetland Functions...... 9-4 Variation of Functions Over Time ...... 9-4 Protection of Wetland Functions...... 9-5 9.2.3 Existing Protection Methods ...... 9-5 Buffers...... 9-5 Stormwater Management ...... 9-8 Wetland Mitigation ...... 9-9 Watershed and Landscape Protection ...... 9-13 Ecosystem Level Management Based on Functional Criteria ...... 9-13 Wetland Functions and Their Protection at Four Spatial Scales...... 9-14 9.3 CONCLUSION ...... 9-47 9.4 LITERATURE REFERENCES ...... 9-48

APPENDIX A – BEST AVAILABLE SCIENCE RULE ...... A-1

APPENDIX B – STORMWATER ...... B-1

APPENDIX C ...... C-1

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