D ETERMINING THE ORDINARY HIGH WATER MARK ON STREAMS IN WASHINGTON STATE Dr. Patricia Olson and Erik Stockdale, Shorelands & Environmental Assistance Program, Washington State Department of Ecology Ecology Publication #: 08-06-001 March 2010 Second Review Draft DETERMINING THE ORDINARY HIGH WATER MARK ON STREAMS IN W ASHINGTON STATE March 2010 Second Review Draft Dr. Patricia Olson and Erik Stockdale Washington State Department of Ecology Shorelands & Environmental Assistance Program Ecology Publication #: 08-06-001 This report should be cited as: Olson, P. and E. Stockdale. 2010. Determining the Ordinary High Water Mark on Streams in Washington State. Second Review Draft. Washington State Department of Ecology, Shorelands & Environmental Assistance Program, Lacey, WA. Ecology Publication # 08-06-001. Cover photographs courtesy of Brian Walsh: Top left: Loretta Creek, Skagit River basin. Top right: White River. Bottom: Stillaguamish River. This document is available (or will be shortly) on the Department of Ecology web site at http://www.ecy.wa.gov/biblio/0806001.html Special accommodations: If you need this publication in an alternate format, call the Shorelands and Environmental Assistance Program at 360-407-6096. Persons with hearing loss, call 711 for Washington Relay Service. Persons with a speech disability, call 877-833-6341. DETERMINING THE OR DINAR Y HIGH WATER MAR K ON STRE AMS IN WASHIN GTON STATE Table of Contents Chapter One - Introduction ......................................................................................................................................................................... 1 Importance of accurate Ordinary High Water Mark determinations ................................................................................. 1 Purpose of the document ........................................................................................................................................................................ 2 Organization of this document ............................................................................................................................................................. 3 Chapter Two – defining the ordinary high water mark ................................................................................................................. 5 The ordinary high water mark defined ............................................................................................................................................ 5 The three criteria of ordinary high water mark ........................................................................................................................... 6 What is ordinary high water mark on a stream? .......................................................................................................................... 8 Reasons for systematically determining the OHWM ................................................................................................................ 10 Common misunderstandings of stream OHWM ......................................................................................................................... 11 OHWM on tidally influenced streams.............................................................................................................................................. 16 Chapter THREE – Office Assessment .................................................................................................................................................... 19 Step 1: Assess landscape and geomorphic features .................................................................................................................. 19 Step 2: Choose potential locations for field survey ................................................................................................................... 21 Importance of hydrologic assessment ............................................................................................................................................ 24 Chapter FOUR - Field Assessment ......................................................................................................................................................... 25 General observations .............................................................................................................................................................................. 25 Identify lower and upper boundaries of OHWM using transects: ...................................................................................... 26 - Set up transects from the water’s edge to the upland. ................................................................................................. 26 - Identify vegetation and soil indicators along transect starting at water’s edge. .............................................. 26 Narrow the bookends ............................................................................................................................................................................. 28 Field indicators .......................................................................................................................................................................................... 30 Chapter FIVE – Hydrologic Assessment .............................................................................................................................................. 43 Step 5-1: Use gage data to approximate upper and lower Values of OHW flow .......................................................... 44 Step 5-2: Evaluate peak flow “bookends” using daily discharge and stage data ......................................................... 46 MARCH 2010 SECOND REVI EW D RAFT i DETERMINING THE OR DINAR Y HIGH WATER MAR K ON STRE AMS IN WASHIN GTON STATE Step 5-2.1: Convert discharge to stage ........................................................................................................................................... 48 Step 5-3: Compare recent events to OHWM bookends ........................................................................................................... 50 MARCH 2010 SECOND REVI EW D RAFT ii DETERMINING THE OR DINAR Y HIGH WATER MAR K ON STRE AMS IN WASHIN GTON STATE List of Figures Figure 2-1: Deschutes River daily mean discharge for 1996-2008 . ....................................................................... 10 Figure 2-2: Comparisions of recurrence interval for small, frequent peak flows ................................................ 10 Figure 2-3: Cross-section of a typical stream showing OHWM .............................................................................. 12 Figure 2-4: Channel characteristics that influence the location OHWM ................................................................ 13 Figure 2-5: Cross-section from a multi-channel stream reach .................................................................................... 15 Figure 2-6: Example cross-sections from the intertidal zone to upstream of tidal influence .............................. 17 Figure 3-1: Determinations where indicators are not available on site ................................................................ 22 Figure 4-1: An example of cross-sectional profile illustrating some channel and floodplain feature ................. 27 Figure 5-1: Deschutes River peak streamflow for 1950-2006 ................................................................................. 46 Figure 5-2: Deschutes River daily mean discharge for 1996-2009 ......................................................................... 47 Figure 5-3: Deschutes River discharge to stage conversion .................................................................................... 49 List of Tables Table 3-1. Location of OHWM in relation to channel pattern 23 Table 4-1. Selected OHWM indicators and locations 41 Appendices Appendix A: Field Data Form Appendix B: Plant Species Distribution Across OHWM Gradient Appendix C: Internet Links Appendix D: Geomorphic Examples and Indicators Appendix E: Example Report Outline Appendix F: Glossary Appendix G: Comparison of different OHWM definitions in various statutes and rules Appendix H: References and Suggested Reading MARCH 2010 SECOND REVI EW D RAFT iii DETERMINING THE OR DINAR Y HIGH WATER MAR K ON STRE AMS IN WASHIN GTON STATE This page left intentionally blank. MARCH 2010 SECON D R E VIEW DRAFT iv DETERMINING THE OR DINAR Y HIGH WATER MAR K ON STRE AMS IN WASHIN GTON STATE Acknowledgements The production of this document would not have been possible without the assistance and input from others. We would like to acknowledge the long-standing effort by Perry Lund of the Department of Ecology to develop a science-based methodology for determining the location of the Ordinary High Water Mark (OHWM) on shorelines of the state. We are equally indebted to Al Wald of the Department of Fish & Wildlife who similarly recognized the need for a consistent, inter-agency guidance document. We hope this document will eventually lead in that direction. Both Al and Perry have contributed hundreds of hours in providing training for local, state, federal and tribal staff, and consultants. They also provided technical oversight during the initial scoping of the methodology. We are grateful to Marlies Wierenga and Joy Michaud of Envirovision, Inc. (Olympia, WA) who managed the production of the first draft of the document. Thank you for your patience while