USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: Februar 1, 2006
[Note: The report can be viewed on the Web at http://pubs.water.usgs.gov/sir20065005/ .]
Columbia Basin Project irrigation-return water shows increases in concentrations of some pesticides and decreases of others, with most concentrations generally in the middle to lower end of the range, compared to concentrations found in previous studies, according to a report published by the U.S. Geological Survey (USGS).
In cooperation with the Bureau of Reclamation, the USGS studied the quality of return flows in the Red Rock Coulee, Crab Creek, Sand Hollow, and Lind Coulee drainages within the project.
Compared with results from previous USGS studies of the Columbia and Yakima basins, as well as with national agricultural studies, pesticide concentrations in the Columbia Basin Project generally were in the middle to lower end of the range, although the number of times pesticides were detected in the study samples was high.
Results show that concentrations of three insecticides and one herbicide sometimes exceeded U.S. Environmental Protection Agency or Canadian freshwater aquatic-life benchmarks. These aquatic-life benchmarks refer to long-term exposure to lower-level concentrations. Although the concentrations sometimes exceeded benchmarks for long-term exposure, none of them exceeded short-term lethal levels for fish. In the USGS study samples, the benchmarks generally were exceeded in samples taken in June and July, during the middle of the irrigation season.
From July 2002 through October 2004, USGS scientists sampled water from sites in the four irrigation return-flow drainage basins in the project. Samples were analyzed for temperature, pH, specific conductance, dissolved oxygen, major ions, trace elements, nutrients, and a suite of 107 pesticides and pesticide metabolites (compounds resulting from the breakdown of pesticides). Ten samples were collected throughout each irrigation season (generally April through October) and two samples were collected during the nonirrigation season.
The water-quality study conducted for the Bureau of Reclamation builds on the USGS National Water-Quality Assessment program now underway in the Central Columbia Plateau since 1991. This USGS national program uses standardized methods to produce high-quality data to assess the quality of water nationwide. More information about the USGS work in the Central Columbia Plateau is available on the Web at http://wa.water.usgs.gov/projects/ccyk/.
The report, "Pesticides in Agricultural Irrigation-Return Flows from Four Drainage Basins in the Columbia Basin Project, Washington, 2002-04," by Richard J. Wagner, Lonna M. Frans, and Raegan L. Huffman, is published as U.S. Geological Survey Scientific Investigations Report 2006-5005. The report can be viewed on the Web at http://pubs.water.usgs.gov/sir20065005/. 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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