In December 2020, the final results from the Minnesota Department of Agriculture’s (MDA) Township Testing program were published for Houston County. These results are available in both a 69-page report and a 3-page summary. Both of which are available on MDA’s website and Root River SWCD’s website: www.mda.state.mn.us/townshiptestingco.houston.mn.us/departments/soil-and-water.
In short, the program’s goal was to determine which townships have considerable groundwater pollution from nitrate originating from fertilizers used in row crop production.
Two rounds of testing were conducted in 10 selected townships in Houston County which were suspected of being at high risk for nitrate pollution. These townships were: Money Creek, Houston, Sheldon, Union, Black Hammer, Caledonia, Mayville, Spring Grove, Wilmington, and Winnebago.
The first round of testing was conducted by private well owners, who were contacted by the MDA and were sent test kits for them to complete and send-in to a lab. Any wells that had detections of nitrate-N were offered a follow-up site visit by an MDA worker. All homeowners who agreed to participate in the follow-up testing received a free nitrate and pesticide test regardless of age or condition of the well.
Wells were removed from the study if there were possible nitrate sources besides nitrogen fertilizer impacting the well. Only well test results from this second round of testing were included in the final results.
MDA categorized townships into three different categories, based on the percentage of tested wells that had nitrate-N levels greater than or equal to 10 mg/L, which is the health risk limit (HRL). The categories are: less than 5% of tested wells, 5-9.9% of tested wells, and greater than or equal to 10% of tested wells.
Final Results show five townships with greater than or equal to 10% of tested wells above the HRL for nitrates. These townships are: Black Hammer, Caledonia, Mayville, Spring Grove, and Wilmington. The other 5 townships in the study are in the category of less than 5% of tested wells above the HRL.
Interested individuals are encouraged to look at these reports online, for they go into greater detail and break the data down into concise tables, charts, and maps.