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Pesticides in streams of the western Lake Michigan drainages, Wisconsin and Michigan, 1993-95

April 1, 1997

During 1993-95, water samples were collected at nine sites on eight streams in the Western Lake Michigan Drainages to attempt to determine pesticide concentrations. The sampling effort was part of the U.S. Geological Survey's National Water- Quality Assessment (NAWQA) Program. Pesticides analyzed for were 58 herbicides and 30 insecticides. Pesticides are used extensively in the study area; application of herbicides to corn and soybeans accounts for most of the use. Herbicides were detected more frequently and generally at higher concentrations than insecticides. The herbicide atrazine is applied to more acreage in Wisconsin than all other pesticides and was detected in 142 of 143 samples. The herbicides simazine, metolachlor, cyanazine, prometon, and alachlor were detected in more than half of the samples. The presence of these compounds in the sampled streams, is related to agricultural use. Two streams in forested basins in the northern part of the study area were sampled and found to contain low concentrations of atrazine. Atmospheric deposition is the likely source; atrazine has been detected in rain fall in northeastern Wisconsin. Herbicide concentrations in agricultural basins were highest in samples collected during storm runoff following application. Concentrations decreased over the growing season as herbicides broke down and increased ground cover reduced runoff. The U.S. Environmental Protection Agency (USEPA) drinking-water standard for atrazine was exceeded in eight samples, and the standard for alachlor was exceeded in two samples. All exceedances occurred during brief periods of high streamflow in June and July at two streams that drain primarily agricultural basins. Herbicide data for the Western Lake Drainages and other NAWQA study units indicate that concentrations in streams are as much as two orders of magnitude higher in areas where agricultural land contains a high percentage of row crops especially corn and soybeans than in areas where grazing, hay production, and other less herbicide-intensive crops are raised.

Citation Information

Publication Year 1996
Title Pesticides in streams of the western Lake Michigan drainages, Wisconsin and Michigan, 1993-95
DOI 10.3133/fs10796
Authors Daniel J. Sullivan, Kevin D. Richards
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Fact Sheet
Series Number 107-96
Index ID fs10796
Record Source USGS Publications Warehouse
USGS Organization Wisconsin Water Science Center