Minnesota National Lakes Assessment Project: Pesticides in Minnesota Lakes

In 2007 the Minnesota Department of Agriculture (MDA) cooperated with the Minnesota Pollution Control Agency (MPCA) in a statewide assessment of pesticides in Minnesota lakes as part of the National Lakes Assessment Program (NLAP) coordinated by United States Environmental Protection Agency (USEPA). Fifty-three lakes were randomly selected and sampled by MPCA and USEPA staff from throughout the state. Samples were analyzed by the MDA laboratory for 37 commonly used agricultural pesticides and their degradates. Pesticides and/or degradates were detected in 91 percent of the samples collected. The corn herbicide atrazine was the most frequently detected compound. All pesticide detections were well below established water quality standards or USEPA reference values. Pesticide detections were widespread, including many non-agricultural areas of the state. Atmospheric deposition of pesticides is suspected as the primary transport mechanism in non-agricultural areas.