PROGRAM ERITAGE H NATURAL Wetland Conservation Priorities for Western Washington. A Focus on Rare & High-quality Wetland & Riparian Plant Associations WASHINGTON Prepared for U.S. Environmental Protection Agency, Region 10 Prepared by F. Joseph Rocchio, Rex C. Crawford, and Rebecca Niggemann September 30, 2014 Natural Heritage Report 2014-08 Wetland Conservation Priorities for Western Washington. A Focus on Rare & High-quality Wetland & Riparian Plant Associations Washington Natural Heritage Program Report Number: 2014-08 September 30, 2014 Prepared by: F. Joseph Rocchio, Rex C. Crawford, and Rebecca Niggemann Washington Natural Heritage Program Washington Department of Natural Resources Olympia, Washington 98504-7014 .ON THE COVER: (clockwise from top left) South Nolan Creek (North Pacific Lowland Confined Riparian Forest); Marsh Creek (North Pacific Lowland Moderately Rich Sloping Fen, North Pacific Forested Seepage Swamp, Vancouverian Lowland Riverine-Impounded Shrub Swamp ); Elk Lake (North Pacific Lowland Poor Water Track & Floating Bog Mat); and Loomis Lake (Western North American Temperate Freshwater Lowland Floating-leaved Rooted Aquatic Bed). Photograph by: Joe Rocchio Table of Contents Page Table of Contents ............................................................................................................................ ii Figures.......................................................................................................................................... viii Tables .............................................................................................................................................. x Appendices .................................................................................................................................... xii Executive Summary ..................................................................................................................... xiii Acknowledgments...................................................................................................................... xxxi 1 Introduction .................................................................................................................................. 1 1.1 Project Overview ............................................................................................................... 3 1.2 Project Scope and Objectives ............................................................................................ 4 1.2.1 What Types of Wetland Elements Occur in Western Washington? .......................... 6 1.2.2 What is the Biodiversity Significance of the Wetland Elements? ............................. 6 1.2.3 Where Are Known Wetlands of High Conservation Value in Western Washington? ....................................................................................................................... 7 1.2.4 What the Current Protection Status of Known Wetlands of High Conservation Value? ........................................................................................................... 7 1.2.5 Where are Potential New Wetlands of High Conservation Value in Western Washington? ......................................................................................................... 7 1.2.6 What are the Trends in Ecological Integrity, Wetland Functions, and Stressors Associated with Wetlands of High Conservation Value in Western Washington? ....................................................................................................................... 8 1.3 Products and Outputs ......................................................................................................... 8 2 Project Area ................................................................................................................................. 9 2.1 Climate Overview .............................................................................................................. 9 2.2 Geology Overview ............................................................................................................. 9 2.3 Topography and Hydrogeologic Settings ........................................................................ 10 2.4 Ecoregions of Western Washington ................................................................................ 10 2.4.1 Puget Trough Ecoregion .......................................................................................... 11 2.4.2 Northwest Coast Ecoregion ..................................................................................... 14 2.4.3 North Cascades Ecoregion ....................................................................................... 16 ii 2.4.4 West Cascades Ecoregion ........................................................................................ 17 3 Natural Heritage Methodology .................................................................................................. 20 3.1 Natural Heritage Methodology ........................................................................................ 20 3.2 Elements of Biodiversity ................................................................................................. 21 3.2.1 Species ..................................................................................................................... 22 3.2.2 Ecosystems ............................................................................................................... 22 3.3 Element Conservation Status Rank ................................................................................. 23 3.3.1 Conservation Status of Rare Plants .......................................................................... 25 3.3.2 Conservation Status of Ecosystem Elements ........................................................... 25 3.4 Element Occurrences ....................................................................................................... 25 3.4.1 Rare Plant Element Occurrences ............................................................................. 26 3.4.2 Ecosystem Element Occurrences ............................................................................. 26 3.5 Element Occurrence Ranks (Ecological Integrity Assessment Rank) ............................. 26 3.5.1 Rare Plant Element Occurrence Rank...................................................................... 27 3.5.2 Ecosystem Element Occurrence Rank (=Ecological Integrity Rank) ...................... 28 3.6 Determination of Wetland of High Conservation Value Status ...................................... 28 3.6.1 Using Sensitive Plant Species to Designate Wetlands of High Conservation Value ........................................................................................................... 28 3.6.2 Using Ecosystem Elements to Designate Wetlands of High Conservation Value ................................................................................................................................. 29 3.6.3 Proposing New Wetlands of High Conservation Value to Washington Natural Heritage Program ................................................................................................. 29 4 Ecological Integrity Assessment Methods ................................................................................. 31 4.1 Introduction ...................................................................................................................... 31 4.2 Ecological Integrity Assessment Methods ....................................................................... 31 4.2.1 Introduction .............................................................................................................. 31 4.2.2 EIA Approach to Assessing Ecological Condition .................................................. 31 4.2.3 Level 1 Ecological Integrity Assessment ................................................................. 32 4.2.4 Level 2 Ecological Integrity Assessments ............................................................... 33 5 Field Methods ............................................................................................................................ 35 5.1 Prioritizing Field Surveys of Known Plant Association-based Wetlands of High Conservation Value ...................................................................................................... 35 iii 5.2 Prioritizing Field Surveys for Undocumented Wetlands of High Conservation Value. ..................................................................................................................................... 35 5.3 Office Preparations .......................................................................................................... 36 5.4 Mobile Data Collection and Field Forms ........................................................................ 36 5.5 Field Data Collected ........................................................................................................ 39 5.5.1 General Site Characteristics ..................................................................................... 39 5.5.2 Vegetation Data ....................................................................................................... 39 5.5.3 Ecological Integrity Assessment Data ..................................................................... 39 5.5.4 Ecological Observations for Non-targeted Wetlands .............................................. 40 5.5.5 Wetland Function Assessment (Wetland Rating System)