USGS Washington Water Science Center
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Hydrogeologic Unit Extent and Thickness Maps, Johns Creek Subbasin and Vicinity, Mason County, Washington - Completed FY2011
Problem - Johns Creek is an important producer of Coho and chum salmon. In 1984 the Department of Ecology established an Instream Resources Protection Program for Water Resource Inventory Area 14 (WAC 173-514) to retain sufficient in-stream flow to protect fish and wildlife, scenic, aesthetic and other environmental values. This rule closed Johns Creek and its tributaries to all consumptive appropriations annually from September 16 - November 15, and also established minimum instream flows for the rest of the year. Despite these protections Johns Creek stream flows near the mouth have declined to the point that average daily flows now rarely meet the established minimum flow levels from mid-February through September. In response to these changes the Squaxin Island Tribe has petitioned Ecology twice to close the Johns Creek subbasin to all new appropriations (in April 2008 and January 2010) unless impact to surface water are mitigated. However, in order for Ecology to properly develop appropriate management options a better understanding of the hydrogeology of Johns Creek subbasin is needed.
Objectives - The objective of the study is to characterize the hydrogeologic units in the groundwater-flow system in Johns Creek subbasin and vicinity. It is anticipated that these data will eventually be integrated, along with other information, into a numerical flow model to contribute to an improved understanding of water resources in the Johns Creek subbasin.
Relevance and Benefits - This study directly supports USGS mission and goals related to water-resource issues identified in the USGS Science Strategy. This study addresses groundwater availability and sustainability, a priority issue under the Water Census of the United States as outlined in Facing Tomorrow's challenges: USGS Science in the Decade 2007-2017. This study will contribute to the development of a USGS regional-scale assessment of groundwater / surface-water interactions in the Puget Sound Aquifer System, and it will provide resource managers and stake holders in the Johns Creek subbasin with fundamental hydrologeologic data to assist in the development of an improved understanding of water resources and the protection and improvement of its natural resources. This study also will contribute to on-going USGS research into groundwater nutrient loading to southern Hood Canal. This study is appropriate for inclusion in the USGS Cooperative Program because it will provide information that advances understanding of hydrologic processes in a part of the Puget Sound Aquifer System where there is very little existing information.
Approach - Available hydrogeologic data will be compiled and evaluated to construct hydrogeologic unit extent and thickness maps for all aquifer and confining units in the groundwater-flow system in Johns Creek subbasin and vicinity. Hydrogeologic unit extent and thickness data coverages will be produced and formatted to facilitate their direct incorporation into any future groundwater flow model of the study area. Project data will be verified and entered into the USGS National Water Information System data base