1. Prioritizing Watershed Protection in King County
By Olivia Wright

2. 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.

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

4. 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

5. Watersheds In King County

6. 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

7. 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

9. 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

11. 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.

12. 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

14. 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

15. References:
Washington State Geospatial Data Archive (WAGDA).
U.S. Fish and Wildlife Service National Wetlands Inventory (NWI).
State of Washington Department of Ecology.
National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center.