USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: January 20, 2010
[Editors: The report mentioned below is available at http://pubs.usgs.gov/sir/2009/5270 .]
Scientists studying the very complex groundwater-flow system of the lower Skagit River Basin have figured out how the system works, yielding important information that basin water managers need, according to a report published today by the U.S. Geological Survey. The report was produced in cooperation with the Skagit County Public Works Department, Washington State Department of Ecology, and Skagit County Public Utility District No. 1.
Today's new USGS report is the third in a series of four reports that will culminate in a computer model of the lower Skagit River Basin’s groundwater-flow system currently under development by the USGS. Water managers need the computer model to run "what-if" simulations to evaluate the effects of potential future groundwater withdrawals on streamflows in the area.
The USGS study area covers about 247 square miles along the lower Skagit River and its tributary subbasins (East Fork Nookachamps Creek, Nookachamps Creek, Carpenter Creek, and Fisher Creek) in southwestern Skagit County and northwestern Snohomish County. Water level measurements and geologic information from 296 water wells helped scientists define the basin's groundwater-flow system. Streamflow measurements from 27 locations were used to analyze the exchange of water between streams and the groundwater-flow system.
Determining how groundwater flows throughout the study area is not an easy task. "The groundwater-flow system in the lower Skagit River Basin is very complex," said Mark Savoca, USGS hydrologist and lead author of the report. "The different water-bearing units--aquifers--are scattered throughout the basin, and they vary in thickness considerably from location to location, so figuring out how groundwater flows throughout the system was a very good challenge for our scientists." USGS scientists found that most of the late summer streamflow in the tributary subbasins comes from the local aquifers.
The report, "Hydrogeologic Framework, Groundwater Movement, and Water Budget in Tributary Subbasins and Vicinity, Lower Skagit River Basin, Skagit and Snohomish Counties, Washington," by Mark E. Savoca, Kenneth H. Johnson, Steven S. Sumioka, Theresa D. Olsen, Elisabeth T. Fasser, and Raegan L. Huffman, is published as U.S. Geological Survey Scientific Investigations Report 2009-5270 and is available at http://pubs.usgs.gov/sir/2009/5270 .
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