Translate
Groundwater Management Areas
King County has five Groundwater Management Areas (GWMAs) within the county boundaries. These areas are part of the provisions of Washington Administrative Code (WAC) 173-100.
Groundwater is important to streams, lakes and wetlands that support fish and wildlife. About one-third of King County's population relies on groundwater wells for drinking water.
Map of the five groundwater management areas in King County
East King County Groundwater Management Area
The EKC groundwater management area encompasses 225 square miles within the Snoqualmie River Valley. Almost 90% of the water used in this area comes from groundwater sources. The cities of Carnation, Duvall, North Bend, and Snoqualmie have the most development. Outside the cities' limits is low-density residential use and forest and agricultural land uses.
Water Suppliers in East King County
This Groundwater Management Area has 38 Group A and 247 Group B Public Water Systems. Water utilities provide water to most of the residents in this area.
East King County Groundwater Management Plan
This plan has been approved by the Washington State Department of Ecology and the King County Council.
- EKC Groundwater Plan - Management Strategies (3,240KB)
- EKC Groundwater Plan - Area Characterization (2,332KB)
- EKC Groundwater Plan - Area Characterization - Appendices (1,052KB)
- EKC Groundwater Plan - Area Characterization - Figures (2,133KB)
East King County Groundwater maps and figures
- EKC 2005 Map of the Water Levels in the Qva unit
- EKC 2005 Map of the Water Levels in the Qal/Qvr units
- EKC GWMA 1998 Land-use Map
- Groundwater Elevations in Alluvium and Vashon Recessional Outwash Aquifers, East King County/ Snoqualmie Valley and Sammamish
- Groundwater Elevations in Vashon Advance Outwash Aquifers, East King County/ Snoqualmie Valley and Sammamish
- Groundwater Elevations in Upper Coarse-grained Q(A)c Aquifers, East King County/ Snoqualmie Valley and Sammamish
Issaquah Creek Valley Groundwater Management Area
The ICV groundwater management area area encompasses 93 square miles east and southeast of Lake Sammamish. Almost all the water used in this area comes from groundwater sources.
Development is primarily in the cities of Issaquah and Sammamish and along the I-90 corridor. Outside of this urban area there are low-density residential uses, forest, and agricultural lands.
Water Suppliers in Issaquah Creek Valley
This Groundwater Management Area has 22 Group A and 265 Group B Public Water Systems. Water utilities provide water to the majority of the residents in this area.
Issaquah Creek Valley Groundwater Management Plan
This plan has been approved by the Washington State Department of Ecology and the King County Council.
- ICV Groundwater Plan - Volume 1 (6.6MB)
- ICV Groundwater Plan - Volume 2 (21.5MB)
Issaquah Creek Valley Groundwater maps and figures
Redmond–Bear Creek Valley Groundwater Management Area
The RBC groundwater management area encompasses 44 square miles north of Lake Sammamish. Almost all the water used in this area comes from groundwater sources.
Development is primarily in the cities of Redmond and Woodinville. Outside the cities there is low-density residential and neighborhood-oriented commercial land uses.
Water Suppliers in Redmond–Bear Creek Valley
This Groundwater Management Area has 5 Group A and 107 Group B Public Water Systems. Water utilities provide water to most of the residents in this area.
Redmond–Bear Creek Valley Groundwater Management Plan
This plan has been approved by the Washington State Department of Ecology and the King County Council.
- RBC Groundwater Plan - Management Strategies (3,541KB)
- RBC Groundwater Plan - Management Strategies - Appendices (545KB)
- RBC Groundwater Plan - Area Characterization (2,491KB)
- RBC Groundwater Plan - Area Characterization - Figures (15,196KB)
Redmond–Bear Creek Valley Groundwater Maps and Figures
South King County Groundwater Management Area
The SKC groundwater management area encompasses 260 square miles within the Green–Duwamish River Watershed. The majority of the water used comes from groundwater sources.
The development is primarily within the cities of Algona, Auburn, Black Diamond, Burien, Covington, Des Moines, Federal Way, Kent, Maple Valley, Milton, Normandy Park, Pacific, Renton, Seatac, Seattle, and Tukwila. Outside the cities' limits has low density residential, forest and agricultural land uses.
Water Suppliers in South King County
This Groundwater Management Area has 42 Group A and 441 Group B Public Water Systems. Water utilities provide water to most of the residents in this area.
South King County Groundwater Management Plan
- SKC Groundwater Plan - Management Strategies - DRAFT July 2003 (3,941KB)
- SKC Groundwater Plan - Supplement - DRAFT July 2003 (2,091KB)
South King County Groundwater Maps and Figures
- South King County GWMA 1998 Land-use Map (214KB)
- Potentiometric Surface in the Qva Aquifer and Water Levels in the Qal Aquifer, South King County
- Potentiometric Surface in the Q(A)c Aquifer, South King County
In South King County, in lieu of a groundwater committee, utility purveyors work to protect groundwater.
Vashon-Maury Island Groundwater Management Area
Vashon-Maury Island is an island in the Puget Sound within the boundaries of King County. This island covers about 37 square miles: Vashon Island is 29.7 square miles and Maury Island is 7.0 square miles.
The EPA has designated this area as a sole source aquifer, because it supplies 50 percent of the drinking water for its service area and there are no reasonably available alternative drinking water sources should the aquifer become contaminated. Because of this designation, there are increased protections in place to prevent contamination to the aquifer.
All of Vashon-Maury Island is considered rural and is in Unincorporated King County. The Island has low residential density, forest and agricultural land uses along with a rural town center.
Water Suppliers on Vashon-Maury Island
This Groundwater Management Area has 23 Group A and 124 Group B Public Water Systems. Local precipitation supplies all drinking water sources on the island. Most residents get their drinking water from public water systems
Groundwater Management Plan
- VMI Groundwater Plan - Management Strategies (7,320KB)
- VMI Groundwater Plan - Area Characterization (4,169KB)
- VMI Groundwater Plan - Area Characterization - Figures (1,614KB)
- VMI Groundwater Plan - Entire Plan - all parts (16,804KB)
Vashon-Maury Island Groundwater Map and Figures
- 2006 Gauge sites on VMI
- Groundwater Monitoring Sites in 2006
- Rainfall Contour map of VMI
- Groundwater table elevation map of the Qva aquifer on VMI
- 2005 Gauging Sites on VMI
- 2005 Groundwater Monitoring Sites on VMI
- VMI GWMA 1998 Land-use Map
Vashon-Maury Island Groundwater Protection Committee
The committee develops strategies to protect Vashon-Maury Island's groundwater.