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The US Geological Survey produced two studies specifically for King County Groundwater Management Plans:

  • D.G. Woodward, F.A.Packard, N.P.Dion, and S.S. Sumioka. Occurrence and Quality of Ground Water in Southwestern King County, Washington. Water-Resources Investigations Report 92-4098. Prepared in cooperation with: State of Washington Dept. of Ecology, Regional Water Association of South King Co., and Seattle - King County Dept. of Public Health. Tacoma. 1995.
  • G.L. Turney, S.C. Kahle, and N.P.Dion. Geohydrology and Ground-Water Quality of East King County, Washington. Water-Resources Investigations Report 94-4082. Prepared in cooperation with Seattle - King County Dept. of Public Health. Tacoma. 1995.

The areas covered by these studies correspond closely to the South King County (214K Acrobat) and East King County (877K Acrobat) Groundwater Management Areas. The map plates below show the extent of the aquifers in these areas, and the contours for the water table at the time, or potentiometric surface, in those area aquifers.

Geohydrologic Unit Label Geohydrologic Unit Name
(layer of soil underground)
Predominant Hydrologic Significance
(does it hold water?*)
Potent. Surface Map (South**) Potent. Surface Map (East)
Qal Alluvium Aquifer (some confining beds) Plate 3(a)
(.pdf, 158K)
Plate 3(b) (.pdf, 253K)
Qvr Vashon Recessional Outwash Aquifer   Plate 3(b) (.pdf, 253K)
Qvt Vashon Till Confining Bed    
Qva Vashon Advance Outwash Aquifer Plate 3(a)
(.pdf, 158K)
Plate 3(c) (.pdf, 261)
Q(A)f Upper fine-grained unit Confining Bed    
Q(A)c Upper coarse-grained unit Aquifer Plate 3(b)
(.pdf, 136K)
Plate 3(d) (.pdf, 247K)
Q(B)f Lower fine-grained unit Confining Bed    
Q(B)c Lower coarse-grained unit Aquifer    
Q(C) or Q(C)u Deepest unconsolidated and undifferentiated deposits Variable    
Br Bedrock (East King Co. only) Aquifer (but unreliable)    

* An aquifer yields water, while a confining bed does not.

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.