The Minnesota Department of Agriculture (MDA) is currently sampling over 160 monitoring wells, naturally occurring springs and private drinking water wells throughout the state. Although concentrations typically remain well below health risk levels, five pesticides have been detected frequently enough to be placed in "common detection" status. This list includes acetochlor, alachlor, atrazine, metolachlor, and metribuzin. These pesticides are being watched and alternative management practices are promoted whenever levels rise.
In 1987, the Minnesota Legislature amended the Minnesota Pesticide Control Law (Minnesota Statute 18B.04). It directed the Minnesota Department of Agriculture (MDA) to determine the impact of pesticides on the environment, including the impacts on surface water and groundwater.
In response to this charge, the MDA initiated a pesticide groundwater monitoring program in 1987 and in 1991, began surface water monitoring. The MDA has one of the most comprehensive pesticide monitoring programs in the country.
In 2015, 734 pesticide samples were collected from 167 sampling locations.
View more detailed Water Monitoring Reports and Resources.
The graphic illustrates long term concentration of metolachlor ESA, a breakdown product of the pesticide metolachlor. It is the most frequently detected pesticide compound in groundwater in the state.
The data in the graphic is from the Central Sands Region, located in the central part of the state. Data indicates that in this area, the 75th percentile and 90th percentile metolachlor ESA concentration trends have been decreasing, while the median concentration trend has been increasing. The detected concentrations are well below any health reference values.
The MDA is currently implementing a comprehensive groundwater monitoring initiative focused on sampling private wells for pesticides. It includes sampling thousands of wells in sensitive geologic conditions in the agricultural areas of the state.
The MDA is also evaluating changing groundwater conditions in areas undergoing conversion from forest to irrigated agriculture.