USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: June 25, 2008
[Note to Editors: The report is available on-line at http://pubs.usgs.gov/sir/2008/5078 ]
For the first time, scientists have directly measured the ground water flow into Hood Canal, one of several pathways that oxygen-depleting nitrate can take to the Canal and could cause fish kills, according to a report published by the U.S. Geological Survey (USGS), in cooperation with the Hood Canal Dissolved Oxygen Program (HCDOP).
The HCDOP is a partnership of more than 30 organizations that monitor and study Hood Canal and, in collaboration with others, evaluate actions to reduce the impacts of the low dissolved oxygen problem.
Low dissolved oxygen concentrations in Hood Canal threaten marine life primarily in late summer and early autumn. The problem is caused by excess algae growth in the surface layer that is driven mainly by nitrate inputs from rivers, seawater, and ground water. In the deep water, oxygen is used up by the decomposition of algae.
Although the largest source of nitrate is seawater, ground water also contributes nitrate, which could be significant during the critical summer months, when algae growth can accelerate and the human population is at its yearly peak.
"Since the 1940s, scientists have been looking for better ways to measure ground-water flow directly," said Bill Simonds, USGS hydrologist and lead author of the report. "To directly measure the quantity of ground water entering Hood Canal, the USGS used several techniques, including the first use in the Pacific Northwest of a new electrical resistivity method."
Nitrate concentrations in ground water are similar to those found in the area streams. The yearly average ground-water flow to the Lynch Cove area of Hood Canal was about equal to a small stream--about 170 cubic feet per second. Computer models of the Hood Canal marine system will be continually evaluated throughout the summer and will include ground water as one of the sources of nitrate.
The report, "Estimates of Nutrient Loading by Ground-Water Discharge into the Lynch Cove Area of Hood Canal, Washington," by F. William Simonds, Peter W. Swarzenski, Donald O. Rosenberry, Christopher D. Reich, and Anthony J. Paulson, is published as U.S. Geological Survey Scientific Investigations Report 2008-5078. Copies of the report will be available at the Hood Canal Science Summit, June 30, 10:00 a.m. to 4:00 p.m., Kitsap Conference Center, Bremerton, hosted by Congressman Norm Dicks. Limited seating available, RSVP required; contact firstname.lastname@example.org, (253) 593-6536. Copies can also be purchased from the U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225-0286, telephone 303-202-4200. It can also be viewed on the Web at http://pubs.usgs.gov/sir/2008/5078 .
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