LOWER DUWAMISH WATERWAY SLIP 4EARLY ACTION AREA BIOLOGICAL ASSESSMENT Submitted to U.S. Environmental Protection Agency, Region 10 1200 Sixth Avenue Seattle, WA 98101 Submitted by City of Seattle King County Prepared by 7900 SE 28th Street, Suite 410 Mercer Island, WA 98040 February 9, 2007 Revised by EPA on *634956* October 7, 2010 634956 LOWER DUWAMISH WATERWAY SLIP 4EARLY ACTION AREA BIOLOGICAL ASSESSMENT Submitted to U.S. Environmental Protection Agency, Region 10 1200 Sixth Avenue Seattle, WA 98101 Submitted by City of Seattle King County Prepared by 7900 SE 28th Street, Suite 410 Mercer Island, WA 98040 February 9, 2007 Revised October 7, 2010 to include New Listing Dates for Steelhead, Federal Delisting date for Bald Eagle, and and updated schedule (Figure 2-2). Biological Assessment Lower Duwamish Waterway Slip 4 Early Action Area February 9, 2007 CONTENTS LIST OF FIGURES ................................................................................................................ vii LIST OF TABLES .................................................................................................................. vii ACRONYMS AND ABBREVIATIONS..............................................................................ix 1 INTRODUCTION........................................................................................................................1Ȭ1 1.1 PROJECT BACKGROUND ..............................................................................................1Ȭ1 1.2 ACTION AREA..................................................................................................................1Ȭ3 1.2.1 Historical Conditions..........................................................................................1Ȭ3 1.2.2 Current Conditions .............................................................................................1Ȭ4 1.3 REPORT ORGANIZATION.............................................................................................1Ȭ4 2 DESCRIPTION OF THE PROPOSED ACTION....................................................................2Ȭ1 2.1 GEORGETOWN STEAM PLANT OUTFALL ...............................................................2Ȭ1 2.2 PIER DEMOLITION..........................................................................................................2Ȭ2 2.3 REMOVAL OF TIMBERS, PILING, AND DEBRIS.......................................................2Ȭ3 2.4 BANK EXCAVATION AND DREDGING.....................................................................2Ȭ3 2.5 SEDIMENT CAPPING......................................................................................................2Ȭ4 2.6 CONSTRUCTION BMPS, OPERATIONAL CONTROLS, AND EQUIPMENT OPTIONS ..................................................................................................2Ȭ6 2.7 LONGȬTERM MONITORING PLAN AND MAINTENANCE ................................2Ȭ10 3 BASELINE OR EXISTING ENVIRONMENTAL CONDITIONS......................................3Ȭ1 3.1 WATER QUALITY ............................................................................................................3Ȭ1 3.1.1 Turbidity...............................................................................................................3Ȭ2 3.1.2 Dissolved Oxygen ...............................................................................................3Ȭ2 3.1.3 Temperature.........................................................................................................3Ȭ3 3.1.4 Contamination .....................................................................................................3Ȭ4 3.2 PHYSICAL HABITAT QUALITY....................................................................................3Ȭ4 3.2.1 Sediment Contamination ...................................................................................3Ȭ4 3.2.2 Water Current Patterns ......................................................................................3Ȭ5 3.2.3 Disturbance/Noise...............................................................................................3Ȭ5 3.3 BIOLOGICAL HABITAT QUALITY...............................................................................3Ȭ5 3.3.1 Estuarine Habitat.................................................................................................3Ȭ5 3.3.2 Benthic Habitat ....................................................................................................3Ȭ5 3.3.3 Forage Fish ...........................................................................................................3Ȭ6 Integral Consulting Inc. iii Biological Assessment Lower Duwamish Waterway Slip 4 Early Action Area February 9, 2007 4 BIOLOGICAL RESOURCES......................................................................................................4Ȭ1 4.1 HABITAT TYPES ...............................................................................................................4Ȭ1 4.2 BENTHIC INVERTEBRATES ..........................................................................................4Ȭ2 4.2.1 Benthic Community............................................................................................4Ȭ2 4.2.2 Shellfish ................................................................................................................4Ȭ3 4.3 SALMONIDS......................................................................................................................4Ȭ3 4.3.1 Chinook, Coho, and Chum Salmon..................................................................4Ȭ4 4.3.2 Steelhead...............................................................................................................4Ȭ5 4.3.3 Coastal Cutthroat ................................................................................................4Ȭ6 4.3.4 Bull Trout..............................................................................................................4Ȭ6 4.4 FORAGE FISH SPECIES ...................................................................................................4Ȭ7 4.5 MAMMALS ........................................................................................................................4Ȭ8 4.6 BIRDS...................................................................................................................................4Ȭ8 4.6.1 Bald Eagle.............................................................................................................4Ȭ9 4.6.2 Peregrine Falcon..................................................................................................4Ȭ9 4.6.3 Purple Martin.....................................................................................................4Ȭ10 5 BIOLOGICAL REQUIREMENTS OF FEDERALȬ AND STATEȬLISTED SPECIES.......5Ȭ1 5.1 PUGET SOUND CHINOOK SALMON .........................................................................5Ȭ1 5.2 PUGET SOUND STEELHEAD ........................................................................................5Ȭ2 5.3 COASTAL/PUGET SOUND BULL TROUT...................................................................5Ȭ3 5.4 BALD EAGLE.....................................................................................................................5Ȭ4 6 EFFECTS OF THE PROPOSED ACTION ...............................................................................6Ȭ1 6.1 EFFECTS ON WATER QUALITY ...................................................................................6Ȭ1 6.1.1 Turbidity...............................................................................................................6Ȭ2 6.1.2 Dissolved Oxygen ...............................................................................................6Ȭ3 6.1.3 Temperature.........................................................................................................6Ȭ3 6.2 EFFECTS ON PHYSICAL HABITAT QUALITY...........................................................6Ȭ3 6.2.1 Sediment Quality.................................................................................................6Ȭ3 6.2.2 Estuarine Habitat Conditions............................................................................6Ȭ4 6.2.3 Shoreline Habitat Conditions ............................................................................6Ȭ4 6.2.4 Disturbance/Noise...............................................................................................6Ȭ5 6.3 EFFECTS ON BIOLOGICAL HABITAT QUALITY......................................................6Ȭ5 6.3.1 Biological Resources ...........................................................................................6Ȭ5 6.3.2 Benthic Prey Availability ...................................................................................6Ȭ6 6.3.3 Forage Fish Availability .....................................................................................6Ȭ7 6.3.4 Intertidal Vegetation...........................................................................................6Ȭ8 Integral Consulting Inc. iv Biological Assessment Lower Duwamish Waterway Slip 4 Early Action Area February 9, 2007 6.3.5 Riparian Vegetation ............................................................................................6Ȭ8 6.4 INTERRELATED, INTERDEPENDENT, AND CUMULATIVE EFFECTS...............6Ȭ8 7 EFFECTS DETERMINATIONS.................................................................................................7Ȭ1 7.1 PUGET SOUND CHINOOK SALMON .........................................................................7Ȭ1