Johnson Creek Watershed Council P.O. Box 82584 Portland, Oregon 97282 TABLE OF CONTENTS TABLE OF CONTENTS.............................................................................................................................................I ACRONYMS AND ABBREVIATIONS .................................................................................................................. V ACKNOWLEDGMENTS .....................................................................................................................................VIII EXECUTIVE SUMMARY......................................................................................................................................... 1 CHAPTER 1.0 INTRODUCTION ..................................................................................................................... 1 1.1 PURPOSE................................................................................................................................................ 1 1.2 SCOPE OF PROJECT............................................................................................................................. 1 1.3 PROJECT GOALS .................................................................................................................................. 1 1.4 ROLE OF JCWC AND TAC................................................................................................................... 1 1.5 RELATIONSHIP TO OTHER PLANNING EFFORTS......................................................................... 2 1.6 COMPLETED AND ONGOING PROJECTS ........................................................................................ 3 1.6.1 Portland Watershed Revegetation Program.......................................................................................... 4 1.6.2 Johnson Creek Restoration Plan........................................................................................................... 4 1.6.3 Lents Flood Management Alternatives.................................................................................................. 5 1.6.4 Lower Willamette Agricultural Water Quality Management Area........................................................ 5 CHAPTER 2.0 WATERSHED ASSESSMENT ................................................................................................ 6 2.1 INTRODUCTION ................................................................................................................................... 6 2.2 WATERSHED DESCRIPTION.............................................................................................................. 7 2.2.1 General Location and Size .................................................................................................................... 7 2.3 JURISDICTIONS AND SUB-WATERSHEDS...................................................................................... 7 2.4 LANDSCAPE FACTORS....................................................................................................................... 9 2.4.1 Topography ........................................................................................................................................... 9 2.4.2 Soils....................................................................................................................................................... 9 2.5 BUILT ENVIRONMENT CONDITIONS............................................................................................ 10 2.5.1 Land Use ............................................................................................................................................. 10 2.5.2 Current Development .......................................................................................................................... 10 2.5.3 Future Development............................................................................................................................ 10 2.5.4 Impervious Surfaces ............................................................................................................................ 13 2.5.5 Roads................................................................................................................................................... 15 2.5.6 Channelization .................................................................................................................................... 15 2.5.7 Water Rights........................................................................................................................................ 15 2.6 WATERSHED CONDITIONS ............................................................................................................. 16 2.7 FLOW AND HYDROLOGY ................................................................................................................ 20 2.7.1 Gradient .............................................................................................................................................. 20 2.7.2 Flow..................................................................................................................................................... 20 2.7.3 Flooding .............................................................................................................................................. 21 2.7.4 Baseflows ............................................................................................................................................. 24 2.8 PHYSICAL HABITATS WITHIN THE JOHNSON CREEK WATERSHED .................................... 27 2.8.1 Upland Habitat.................................................................................................................................... 27 2.8.2 Wetlands.............................................................................................................................................. 27 2.8.3 Riparian Areas .................................................................................................................................... 28 2.8.4 Instream Habitat ................................................................................................................................. 29 2.9 WATER QUALITY .............................................................................................................................. 34 2.9.1 Baseline Ambient................................................................................................................................. 35 2.9.2 Storm Event Sampling ......................................................................................................................... 35 2.9.3 Dissolved Oxygen (DO)....................................................................................................................... 36 2.9.4 Nutrients and Eutrophication.............................................................................................................. 36 2.9.5 Sediment and Turbidity ....................................................................................................................... 36 2.9.6 Metals.................................................................................................................................................. 36 Johnson Creek Watershed Action Plan i 2.9.7 Temperature, Toxics, Bacteria and 303(d) List................................................................................... 37 2.10 BIOLOGICAL COMMUNITIES.......................................................................................................... 41 2.10.1 Fish................................................................................................................................................. 41 2.10.2 Culvert Crossing Inventory............................................................................................................. 45 2.10.3 Refugia............................................................................................................................................ 48 2.10.4 Benthic Macroinvertebrates ........................................................................................................... 48 2.10.5 Wildlife ........................................................................................................................................... 50 2.11 WATERSHED PROBLEMS AND OPPORTUNITIES ....................................................................... 52 2.11.1 Overview......................................................................................................................................... 52 2.11.2 Data Needs ..................................................................................................................................... 52 2.11.3 Assessment of Risks ........................................................................................................................ 53 2.12 KEY LIMITING FACTORS (PROBLEMS) ........................................................................................ 54 2.12.1 Ecosystem Diagnosis and Treatment (EDT) Modeling................................................................... 54 2.13 HIGH PRIORITY AREAS AND ACTIONS ........................................................................................ 63 2.13.1 Protection ....................................................................................................................................... 64 2.13.2 Restoration ....................................................................................................................................