Water quality in the 1,700 square-mile Anoka Sand Plain aquifer in east-central Minnesota is influenced by irrigated and nonirrigated agriculture, and by residential land use. Concen- trations of sulfate, chloride, nitrite plus nitrate nitrogen, and pesticides in ground water are related to human activities, but nitrite plus nitrate nitrogen concentrations are affected more than are concentrations of other chemical constituents. Of the water samples collected from 100 wells during this study, samples from 30 wells had a concen- tration of nitrate plus nitrate nitrogen greater than 10 mg/L (milligrams per liter), the limit recommended for drinking water by the Minnesota Pollution Control Agency. Analysis of 360 samples indicated that the median concentrations of nitrite plus nitrate nitrogen for undeveloped, nonirrigated cultivated, irrigated, and residential lands were 0.22, 2.0, 5.3, and 4.2 mg/L, respectively. Differences in nitrite plus nitrate nitrogen con- centrations with depth below the water table were statistically significant. Median concentrations of nitrite plus nitrate nitrogen in ground-water samples less than 10 feet, 10 to 20 feet, and more than 20 feet below the water table were 5.1, 2.7, and less than 0.1 mg/L, respectively. Seasonal fluctuations in nitrite plus nitrate nitrogen concentrations at many wells were as great or greater than long-term change; however, the springtime median concentrations of nitrite plus nitrate nitrogen increased steadily from 1984 through 1987, from 4.8 to 5.5 mg/L. Triazine herbicides were detected in 11 of the 18 samples analyzed for pesticides. Concentrations of atrazine were less than the 3 ug/L maximum contaminant level set for atrazine by the Minnesota Department of Health and the U.S. Environmental Protection Agency.
Additional Publication Details
USGS Numbered Series
Effects of agricultural and residential land use on ground-water quality, Anoka Sand Plain Aquifer, east-central Minnesota
Water-Resources Investigations Report
U.S. Geological Survey ;
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