USGS Washington Water Science Center
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WA339 - Conceptual and Numerical Models of the Ground-Water System of Thurston County, Washington - Completed FY1999
Problem - The study area comprises about 675 square miles in Thurston County. The study area, for the most part, is a drift-covered glacial plain with four major peninsulas extending into Puget Sound. Demand for water has steadily increased in recent years due to rapid population growth. Thurston County now relies entirely on groundwater for new supplies of water for domestic, public-supply, agricultural, and industrial uses. The County Health Department has recognized the need for a tool (numerical ground-water model) to help assess the response of the ground-water system to future development.
Objectives - The objectives are to build a conceptual model of the ground-water system to the extent allowed by existing data, and then to construct a numerical model which can be used to test the regional effects of proposed development.
Approach - Extend the existing geohydrologic interpretation for the northern part of Thurston County to include all of the unconsolidated sediments in the County. Modify the existing conceptual model as necessary to fit the expanded area and then construct and calibrate a steady-state numerical model of the system. This numerical model will be used, in conjunction with a particle-tracker, to estimate selected recharge areas and to test the effects of selected development scenarios.