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King County has five groundwater management areas (GWMAs) within the county boundaries: East King County, Issaquah Creek Valley, Redmond Bear Creek Valley, South King County and Vashon-Maury Island.  These areas were proposed and designated in 1986-1987 under the provisions of Washington Administrative Code (WAC) 173-100.

Map of Groundwater Management Areas
East King County Groundwater Management Area Issaquah Creek Valley Groundwater Management Area Redmond-Bear Creek Valley Groundwater Management Area South King County Groundwater Management Area Vashon-Maury Island Groundwater Management Area

King County Groundwater Management Areas

East King County
This Groundwater Management Area encompasses most of the Snoqualmie River Valley. The boundaries extend from the Snohomish -King County border to areas south of North Bend, bounded on the east by the foothills of the Cascade Mountains and on the west by the surface water divide between the Bear Creek basin and the Snoqualmie River.

Issaquah Creek
This Groundwater Management Area is located east and southeast of Lake Sammamish.  The boundaries are defined by the drainage of Tibbetts Creek and Issaquah Creek watersheds and the water service area of Sammamish Plateau Water and Sewer District.

Redmond-Bear Creek
This Groundwater management area is located north of Lake Sammamish.  The boundaries run from the Snohomish -King County border up to the water service area of Sammamish Plateau Water and Sewer District. It is bounded on the west by the Sammamish River and on the east by the surface water divide between the Bear Creek basin and the Snoqualmie River.

South King County
This Groundwater Management Area is the largest of the five GWMAs in King County.  Extending from West Seattle to Federal Way and east to Black Diamond, this area encompasses most of the Green-Duwamish Watershed.

Vashon-Maury Island
This Groundwater Management Area encompasses all of Vashon-Maury Island.  This area is an EPA designated Sole Source aquifer. 

This page is produced by the King County Groundwater Protection Program. To learn more about this group and its responsibilities, please read about the Groundwater Protection Program.