USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: August 2, 2004
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[Note: The report can be viewed on the Web at http://pubs.water.usgs.gov/sir20045084/ .]
Mercury concentrations in sediments deposited in the 1990s in Whatcom County lakes show decreases that follow global trends, according to a report published by the U.S. Geological Survey (USGS). The report was published in cooperation with the Whatcom County Health Department and the Washington State Department of Ecology.
Concerns about possible mercury contamination in Lake Whatcom were raised in the late 1990s after a watershed protection survey by the Washington State Department of Ecology reported elevated concentrations of mercury in smallmouth bass. A second study, conducted soon after by the Whatcom County Health Department and several state agencies to help assess the human health risk from eating fish from the lake, confirmed that concentrations in smallmouth bass from the lake were greater than the national average.
Potential sources of mercury to the lakes include global atmospheric deposition, erosion of soils that contain trace amounts of mercury, and emissions from a chlor-alkali plant and municipal waste incinerators in the Bellingham area. The chlor-alkali plant operated from the early 1960s until 2000, and the municipal waste incinerators began operations about 1974.
In the USGS study, mercury concentrations in dated sediment core samples indicate that increases in mercury in sediments were largest during the first half of the 20th century. The increases were probably caused by greater regional and global air emissions. Changes of mercury in the sediment cores with time were not associated with the opening of chlor-alkali plant in 1964 or the operation of the first municipal incinerator in 1974. Mercury concentrations decreased in sediments that were deposited after 1997 in Samish Lake, Fazon Lake, and the northernmost basin of Lake Whatcom; and in the sediments of Lake Terrell around 1990.
The USGS developed a computer model that related air emissions of mercury from the chlor-alkali plant and the municipal waste incinerators to air deposition on the surface of the lakes. Concentration trends in largemouth bass across the area did not seem to be related to the model-estimated deposition from local air emission sources. Likewise, concentration trends in lake sediments over time and area also did not seem to be related to local air emissions.
A public presentation of the report findings is planned for Bellingham in September.
The report, "Sources of Mercury in Sediments, Water, and Fish of the Lakes of Whatcom County, Washington," by Anthony J. Paulson, is published as U.S. Geological Survey Science Investigations Report 2004-5084. The report can be viewed on the Web at http://pubs.water.usgs.gov/sir20045084/ . Copies can be purchased from the U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225-0286, telephone 303-202-4200.
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