Best Available Science

VOLUME II ASSESSMENT OF PROPOSED ORDINANCES

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 II ASSESSMENT OF PROPOSED ORDINANCES

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_BAStitle2.ai lpre EXECUTIVE REPORT – BEST AVAILABLE SCIENCE, Volume II – 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 II – 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 II – 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 II, ASSESSMENT – FEBRUARY 2004

TABLE OF CONTENTS

CHAPTER 1 – INTRODUCTION 1.1 INTRODUCTION...... 1 1.1.1 Purpose and Background...... 1 1.1.2 Hazard and Risk Assessments ...... 3 Risk Assessment for Protection of Species and Habitat ...... 3 1.2 OVERVIEW OF POLICY AND LAND-USE CONTEXT...... 4 1.2.1 Urban Growth Areas (UGAs) Context ...... 5 1.2.2 Rural Lands Context...... 7 1.3 REVIEW OF CONTENTS ...... 9 1.4 REFERENCES...... 10

CHAPTER 2 – ASSESSMENT OF CAO FIXED REGULATIONS 2.1 INTRODUCTION...... 1 2.2 OVERVIEW OF THE PROPOSED CRITICAL AREAS ORDINANCE...... 2 Options For CAO Compliance ...... 3 2.3 FLOOD HAZARD AREA ...... 4 Flood Hazard Area Delineation ...... 5 Restrictions on Development to Protect Public Safety ...... 5 2.4 CHANNEL MIGRATION ZONE...... 10 Classification and Definition ...... 10 Restrictions on Development to Protect Public Safety ...... 14 Allowed Alterations...... 15 2.5 GEOLOGIC HAZARD AREAS...... 17 Restrictions on Development to Protect Public Safety ...... 17 Allowed Alterations...... 20 2.6 CRITICAL AQUIFER RECHARGE AREA...... 20 Critical Aquifer Recharge Area Classification ...... 20 Restrictions on Development to Protect Public Safety ...... 21 2.7 AQUATIC AREAS...... 25 Buffers ...... 25 Allowed Alterations...... 29 Mitigation ...... 30 2.8 WILDLIFE AREAS...... 32 Ten “Shall” Species ...... 32

Table of Contents EXECUTIVE REPORT – BEST AVAILABLE SCIENCE Volume II, ASSESSMENT – FEBRUARY 2004

Remaining “Shall” Species...... 47 Wildlife Habitat Network ...... 48 “Should” Species ...... 50 Allowed Alterations...... 50 Mitigation ...... 51 Buffers ...... 51 2.9 WETLANDS...... 52 Wetland Classification...... 52 Buffers ...... 53 Mitigation ...... 56 Allowed Alteration ...... 59

CHAPTER 3 – CAO PLANNING PROGRAMS AND INCENTIVES 3.1 INTRODUCTION - OPTIONS FOR CAO COMPLIANCE...... 1 3.2 FARM PLANNING ...... 1 3.2.1 Flood Hazard Areas Assessment ...... 2 3.2.2 Aquatic Areas Assessment ...... 2 3.2.3 Wildlife Areas Assessment...... 3 3.2.4 Wetlands Assessment ...... 4 3.3 RURAL STEWARDSHIP PLANNING ...... 7 3.2.5 Aquatic Areas Assessment ...... 7 3.2.6 Wildlife Areas Assessment...... 10 3.2.7 Wetlands Assessment ...... 11 3.4 PBRS - AN INCENTIVES PROGRAM...... 13

CHAPTER 4 – ASSESSMENT OF STORMWATER, CLEARING AND GRADING ORDINANCES 4.1 OVERVIEW OF PROPOSED STORMWATER ORDINANCE AND SURFACE WATER DESIGN MANUAL UPDATE ...... 1 Proposed Requirements...... 1 4.2 OVERVIEW OF PROPOSED CLEARING AND GRADING ORDINANCE...... 5 4.3 ASSESSMENT OF PROPOSED STORMWATER CONTROL ORDINANCE...... 6 4.4 ASSESSMENT OF CLEARING RESTRICTIONS ...... 11 4.5 REFERENCES ...... 16

CHAPTER 5 – INSTITUTIONAL CONTEXT 5.1 INTRODUCTION...... 1

Table of Contents EXECUTIVE REPORT – BEST AVAILABLE SCIENCE Volume II, ASSESSMENT – FEBRUARY 2004

5.2 OVERVIEW OF PROGRAMS THAT SUPPORT CRITICAL AREA PROTECTION...... 1 5.3 HIGHLIGHTS OF PROGRAMS BY CRITICAL AREA ...... 4 5.3.1 King County Flood Hazard Reduction Projects and Programs ...... 4 5.3.2 Other King County Management Actions that Contribute to Channel Migration Zone Protection...... 7 5.3.3 Geologic Hazards...... 8 5.3.4 Critical Aquifer Recharge Areas (CARA)...... 8 5.3.5 Aquatic Areas...... 10 5.3.6 Wildlife Areas...... 11 5.3.7 Wetlands ...... 12 5.3.8 Agriculture...... 12 5.4 INSTITUTIONAL RISKS AND UNCERTAINTIES ...... 13

CHAPTER 6 – CONCLUSIONS 6.1 SUMMARY ...... 1 6.2 FLOOD HAZARD AREAS...... 2 6.3 CHANNEL MIGRATION ZONE (CMZ) ...... 2 6.4 GEOLOGIC HAZARD AREAS...... 3 6.5 CRITICAL AQUIFER RECHARGE AREAS (CARA)...... 3 6.6 AQUATIC AREAS...... 4 6.7 WILDLIFE AREAS...... 4 6.8 WETLANDS...... 8 6.9 FINAL CONCLUSION...... 12 6.10 REFERENCES...... 14

APPENDIX A – THE EFFECTS OF AGRICULTURAL OPERATIONS ON CRITICAL AREAS

A.1 LANDSCAPE AND LOCAL EFFECTS OF AGRICULTURAL ACTIVITIES ON CRITICAL AREAS ...... 1 A.1.1 Landscape Effects of Agriculture ...... 1 A.1.2 Local Effects of Agriculture ...... 3 Ecological Traps ...... 12 A.2 BEST MANAGEMENT PRACTICES TO CONTROL THE EFFECTS OF AGRICULTURAL ACTIVITIES ON CRITICAL AREAS...... 14 A.2.1 Vegetated Filter Strips ...... 16 Effectiveness of Vegetated Filter Strips ...... 16 Factors for Determining Appropriate Widths and Composition of Vegetated Filter Strips 19

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Sensitivity of Receiving Waters and Target Organisms ...... 22 A.2.2 Cover Crops...... 23 A.3 POTENTIAL RISKS TO THE FUNCTIONS AND VALUES OF CRITICAL AREAS GIVEN PROPOSED AGRICULTURAL STANDARDS ...... 29 A.3.1 Major Elements of the CAO Proposal ...... 29 A.3.2 Risk Analysis ...... 30 A. CONCLUSIONS...... 35 A.5 REFERENCES...... 35

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