Nitrate is found in private domestic wells throughout Minnesota shows all townships in the state that have collected at least one nitrate test from a private well between 2009 and 2018. The data was collected from four different state programs. All data was aggregated to the township level using the city, township, and unorganized territory layer provided on the Minnesota Geospatial Commons.
Clicking on a township will provide its name and population, the county where it is located, the number of tests collected through each program, and the number of tests at or above 3, 5, and 10 micrograms per liter, or mg/L.
Results from the Township Testing Program were provided at a township level and assembled from PDFs found online. Results from initial testing were used for all townships, except for two in Washington County and three in Morrison County, for which only final test results were provided.
Townships that had completed final testing reported the number of wells at or above a 3, 5, and 10 mg/L nitrate level. This was about two-thirds of the total number of wells tested through the program. The other third of wells reported only the number of wells at or above the legal limit of 10 mg/L. For these townships, it was assumed that tests at or above 10 mg/L were also above 3 and 5 mg/L. Location data and test results were also provided for households that participated in follow-up tests through the township testing program and are included in the results on this map.
Results from the Southeast Volunteer and Central Sands nitrate testing programs were provided as 2-mile-diameter and 1.5-mile-diameter circles, respectively. Each circle contained one or more private domestic wells that had been sampled for nitrate. Results were assigned to the township where the center of each circle was located. Results from the Minnesota Department of Health New Domestic Well program were assigned to the township where each well was located.
Townships shown in green have collected at least one nitrate test but have no results at or above 3mg/L. Townships in yellow have at least one nitrate test at or above 3 mg/L. Townships in orange have at least one nitrate test at or above 5 mg/L and townships in red have at least one nitrate test at or above 10 mg/L the legal limit for nitrate in drinking water.
To see the full methodology, click here.