Prioritizing Watershed Protection in King County By Olivia Wright

Objective King County is approximately 1,400,805 acres and is covered by 8 watersheds. This study will assess the conditions of the watersheds to prioritize watershed protection in King County.

Watershed Health Analysis Watershed Area 303d listed streams Developed land use area Wetlands and Public Parks

Data 2008 Washington Water Quality Assessment 303(d) listed streams Washington 2006 land cover data Washington State Seamless Wetlands Data from National Wetlands Inventory Major Lakes in Washington State Washington Rivers and Connecting Water Bodies Watershed boundaries derived from terrain data King County Boundary Parks

Watersheds In King County

GIS Analysis Processes Spatial Analysis: Extract by Mask, Convert Raster to Polygons Selection Tools: Select by Attributes Analysis Tools: Clip and Spatial Join Other Tools: Join Tables, Export selected data, Calculate Geometry

Watershed Area (acres) 303d Listed Streams 303d listed streams are water bodies that violate water quality standards for one or more pollutant in accordance with the 1972 Clean Water Act. The condition of the watersheds were ranked based on the percentage of 303d listed streams within their boundaries. Watershed Watershed Area (acres) 303d Stream Area (acres) Percent 303d Streams 303d Ranking Cedar River / Lake Washington 234,206.79 8,458.28 3.61% 1 Central Puget Sound 59,006.73 1,721.65 2.92% 2 Duwamish - Green River 314,223.32 8,394.99 2.67% 3 Sammamish River 108,448.83 1,437.96 1.33% 4 Puyallup River 8,178.21 51.19 0.63% 5 Snoqualmie River 426,818.36 979.36 0.23% 6 White River 76,657.65 147.55 0.19% 7 Skykomish 173,264.58 260.97 0.15% 8

Watershed Area (acres) Developed Land Use Highly concentrated developed land use areas increase impervious surface and runoff into streams and have negative impacts on the health of watersheds. The condition of the watersheds were ranked based on the percent of developed land use area within their boundaries. Watershed Watershed Area (acres) Developed (acres) Percent Developed Developed Ranking Puyallup River 8,178.21 3,305.22 40.42% 1 Central Puget Sound 59,006.73 18,490.54 31.34% 2 Cedar River / Lake Washington 234,206.79 60,228.99 25.72% 3 Sammamish River 108,448.83 26,803.07 24.71% 4 Duwamish - Green River 314,223.32 51,741.37 16.47% 5 White River 76,657.65 3,980.31 5.19% 6 Snoqualmie River 426,818.36 13,110.78 3.07% 7 Skykomish 173,264.58 1,892.30 1.09% 8

National Wetland Inventory and Public Parks Wetlands in a watershed act as natural pollutant removal systems and will increase the health of a watershed. Wetlands and public parks were also taken into consideration to determine the feasibility of restoration for watershed protection. They have the potential to cause challenges regarding permitting issues and increasing the cost of watershed restoration. The condition of the watersheds were ranked based on the percent of wetland and park area within their boundaries.

National Wetland Inventory and Public Parks Watershed Watershed Area (acres) Sum of NWI and Park Areas Percent Area Park and NWI Duwamish - Green River 314,223.32 15,085.26 4.80% 1 White River 76,657.65 4,077.81 5.32% 2 Snoqualmie River 426,818.36 27,704.30 6.49% 3 Cedar River / Lake Washington 234,206.79 18,159.10 7.75% 4 Puyallup River 8,178.21 659.12 8.06% 5 Central Puget Sound 59,006.73 7,055.97 11.96% 6 Sammamish River 108,448.83 16,965.19 15.64% 7 Skykomish 173,264.58 149,486.52 86.28% 8

Final Watershed Prioritization Results After ranking the watersheds in King County based on each parameter, an overall watershed prioritization was determined by summing the rankings established for the 303d streams, developed areas, and NWI and public parks. The overall ranking showed the Cedar River / Lake Washington watershed as having the highest need for restoration based on watershed health and restoration feasibility. Watershed 303d Ranking Developed Ranking Park and NWI Ranking Sum of Rankings Final Watershed Prioritization Cedar River / Lake Washington 1 3 4 8 Duwamish - Green River 5 9 2 Central Puget Sound 6 10 Puyallup River 11 Sammamish River 7 15 White River Snoqualmie River 16 Skykomish 24

References: Washington State Geospatial Data Archive (WAGDA). http://wagda.lib.washington.edu/ U.S. Fish and Wildlife Service National Wetlands Inventory (NWI). http://www.fws.gov/wetlands/ State of Washington Department of Ecology. http://www.ecy.wa.gov/ecyhome.html National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center. http://www.csc.noaa.gov/index.html