The study found that agriculture, rather than human waste, is the main source of nitrate and coliform well water contamination
New research by a U.S. Department of Agriculture microbiologist found that nitrate and coliform mostly enter well water supplies through agriculture as opposed to human waste. The study, led by Microbiologist Mark Borchardt, was presented at the Midwest Manure Summit in Green Bay, Wisc., Feb. 27. Borchardt found that more than 60% of wells sampled in Kewaunee County, Wisc., were contaminated with fecal microbes, which can come from septic systems or animal waste.
"Where we see the strong relationships, the strong linkages, those are with agricultural factors. So that would suggest that agriculture is primarily responsible for those two contaminants," Borchardt said in an interview with Wisconsin Public Radio.
The study seeks to identify sources of well water contamination and how certain factors elevate the risk of contaminating drinking water. To assess various factors, the researcher used models to predict how factors can impact contamination levels. Factors assessed include the distance of a well from a manure lagoon or agricultural field, weather, and the quality of well construction.
According to Wisconsin Public Radio, the closest well in the study was 150 ft from a manure pit, yet even wells 3 miles away have a 10% chance of being contaminated. The study investigated nitrate, coliform bacteria, human fecal microbes, bovine fecal microbes and other fecal microbes.
In Wisconsin, drinking water contamination has been a relevant issue with the Legislature’s recent creation of a new bipartisan Water Quality Task Force aimed at improving water quality across the state.