USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: June 2, 1999
Blake Thomas, Hydrologist
(253) 428-3600, ext. 2605
The water resources of the Sequim-Dungeness area of Clallam County--ground water, rivers, and streams-- are highly interconnected, an important factor that could affect threatened Dungeness River salmon as well as new well drilling, according to the results of a new study by the U.S. Geological Survey (USGS).
The study was conducted in cooperation with the Clallam County Department of Community Development and the Washington State Department of Ecology. Assisting in data collection for the project were many local area volunteers, local agencies, and tribal staff.
The population of the Sequim-Dungeness area jumped about 250 percent over the last 20 years. Land use has shifted from agricultural to residential, resulting in more ground water withdrawals. But the area's water resources are limited; average annual precipitation is only about 21 inches.
"Ground water, rivers and streams here are closely connected," said Blake Thomas, USGS hydrologist and lead author of the study's report. "Water from the Dungeness River provides about a half of the area's ground water recharge, either from direct leakage or irrigation. At the same time, much of the flow in smaller streams of the area comes from ground water."
The study looked at several key aspects of the hydrogeology of the area, including ground-water recharge, the extent and thickness of aquifers, ground- water use, and the quality of ground water.
"In samplings from 1980 to 1996, we found a small but significant increase in median nitrate concentrations in ground water," Thomas said. "Higher nitrate concentrations also are more closely related to residential areas than to grasslands or forests."
The report, "Hydrogeologic Assessment of the Sequim-Dungeness Area, Clallam County, Washington," by B.E. Thomas, L.A. Goodman, and T.D. Olsen, is published as USGS Water-Resources Investigations Report 99-4048. The report is available for reading at the USGS, Water Resources Division, 1201 Pacific Avenue, Suite 600, Tacoma, Washington 98402, telephone (253) 428-3600. The report can be purchased from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver, Col- orado 80225, telephone (303) 202-4166. A limited number of free copies of this 165-page report are available from the Clallam County Department of Community Development, 223 East 4th Street, Port Angeles, WA 98362, phone (360) 417-2277. Copies are also available for reading at the North Olympic Library System libraries in Sequim and Port Angeles.
As the nation's largest water, earth, and biological science and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impar- tial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disas- ters, contribute to sound economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.
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