City of Bothell Streams and Riparian Areas: Best Available Science DRAFT Submitted to City of Bothell October 7, 2004 Steward and Associates 120 Avenue A, Suite D Snohomish, Washington 98290 Tel (360) 862-1255 Fax (360) 563-0393 www.stewardandassociates.com Citation: Steward and Associates. 2004. DRAFT - City of Bothell Streams and Riparian Areas: Best Available Science. Prepared for City of Bothell. October, 2004. City of Bothell Streams and Riparian Areas: Best Available Science TABLE OF CONTENTS Table of Contents ..................................................................................................................... i List of tables............................................................................................................................iii Executive summary................................................................................................................. 1 1 Purpose and organization............................................................................................... 3 2 Anadromous Salmon in the Planning Area .................................................................. 4 2.1 Chinook salmon ........................................................................................................ 4 2.1.1 Status..................................................................................................................... 4 2.1.2 Life History........................................................................................................... 5 2.1.3 Habitat Use............................................................................................................ 7 2.2 Coho Salmon............................................................................................................. 8 2.2.1 Status..................................................................................................................... 8 2.2.2 Life History........................................................................................................... 9 2.2.3 Habitat Use............................................................................................................ 9 2.3 Steelhead................................................................................................................. 10 2.3.1 Status................................................................................................................... 10 2.3.2 Life history.......................................................................................................... 10 2.3.3 Habitat use .......................................................................................................... 11 2.4 Sockeye salmon ...................................................................................................... 11 2.4.1 Status................................................................................................................... 11 2.4.2 Life history.......................................................................................................... 12 2.4.3 Habitat use .......................................................................................................... 12 2.5 Kokanee salmon...................................................................................................... 12 2.5.1 Status................................................................................................................... 12 2.5.2 Life history.......................................................................................................... 13 2.5.3 Habitat use .......................................................................................................... 13 3 Salmon Habitat Stressors ............................................................................................. 13 4 Riparian area Structure, Functions and Values ........................................................ 17 4.1 Riparian structure and ecosystem processes........................................................... 17 4.2 Riparian area functions and values ......................................................................... 20 4.3 Riparian buffer function and effectiveness............................................................. 21 4.3.1 Wildlife habitat ................................................................................................... 22 -i- City of Bothell Streams and Riparian Areas: Best Available Science 4.3.2 Temperature and microclimate control............................................................... 23 4.3.3 Sediment removal ............................................................................................... 24 4.3.4 LWD recruitment................................................................................................ 25 4.3.5 Nutrient and pollutant removal ........................................................................... 26 4.3.6 Streambank stabilization..................................................................................... 27 5 City of Bothell Sub-basin Summaries ......................................................................... 27 5.1 Sammamish River Mainstem.................................................................................. 27 5.1.1 Land Use ............................................................................................................. 27 5.1.2 Fish Utilization.................................................................................................... 27 5.1.3 Habitat Conditions .............................................................................................. 28 5.2 North Creek............................................................................................................. 29 5.2.1 Land Use ............................................................................................................. 29 5.2.2 Fish Utilization.................................................................................................... 30 5.2.3 Habitat Conditions .............................................................................................. 30 5.3 North Creek Tributaries .......................................................................................... 31 5.3.1 Coal Creek .......................................................................................................... 31 5.3.2 Palm Creek.......................................................................................................... 32 5.3.3 Perry Creek ......................................................................................................... 32 5.3.4 Queensborough Creek......................................................................................... 33 5.3.5 Joco Creek........................................................................................................... 33 5.3.6 Royal Anne Tributaries....................................................................................... 33 5.3.7 Filbert Creek ....................................................................................................... 34 5.4 Horse Creek ............................................................................................................ 34 5.4.1 Land Use ............................................................................................................. 34 5.4.2 Fish Utilization.................................................................................................... 34 5.4.3 Habitat Conditions .............................................................................................. 34 5.5 Swamp Creek.......................................................................................................... 35 5.5.1 Land Use ............................................................................................................. 35 5.5.2 Fish Utilization.................................................................................................... 35 5.5.3 Habitat Conditions .............................................................................................. 35 5.6 Sammamish Independent Tributaries ..................................................................... 36 5.6.1 Land Use ............................................................................................................. 36 5.6.2 Fish Utilization.................................................................................................... 36 -ii- City of Bothell Streams and Riparian Areas: Best Available Science 5.6.3 Habitat Conditions .............................................................................................. 36 5.7 Unique watershed characteristics............................................................................ 37 6 Synthesis of Best Available Science and Local Conditions ....................................... 38 6.1 Sammamish river mainstem.................................................................................... 38 6.2 North Creek............................................................................................................. 39 6.3 North Creek tributaries ........................................................................................... 39 6.4 Horse Creek ............................................................................................................ 40 6.5 Swamp Creek.......................................................................................................... 40 6.6 Sammamish independent