Mower County water wells show elevated levels of arsenic and manganese
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State health officials report that private well water testing has detected high levels of arsenic and manganese in the wells of some homes in southeast Minnesota’s Mower County.
According to a statement put out by Mower County’s Health & Human Services department, 65 percent of the water samples tested in the county about two hours south of the Twin Cities, had high levels of arsenic. Elevated levels of manganese were identified in 28 percent of the samples.
Allison Ward, a community health educator with Mower County Health & Human Services, said the levels detected aren’t quite high enough to be dangerous to human health yet, but she encourages Minnesotans in the region with private well water to get their water tested as soon as possible.
“This is just situational awareness,” said Ward in an interview with MPR News. “It's good to know your status, and if it is high, it's better to know, because for arsenic, you can't see it, you can't smell it, and you can't taste it in your water. So you're never actually going to know if you're introducing that into your body.”
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Although it can take years of drinking contaminated water to develop symptoms, the health consequences can be serious. Ward said that water contaminated with arsenic can cause both acute and chronic illnesses — including cancers — and cardiovascular and respiratory diseases.
And it's more dangerous for children because they have a lower body weight. Over time, ingesting this contaminated water can lead to impaired brain development and reduced intelligence in kids.
The county recommends well users with arsenic detected at any level consider utilizing a water treatment and filtration system or using another source for drinking water.
The elevated levels were detected as part of a state health program, called the Tap-In initiative, which was launched in 2024. The program offers free water testing kits and analysis to Minnesotans in the southeast region that rely on private wells for their drinking water. So far, the state health department has analyzed 1,381 samples through the program.
The geology and topography of southeast Minnesota is part of what puts well water in the region at risk for contamination. There is a lot of farmland on rolling hills, and it includes some steep ravines, so when it rains, farm waste and fertilizers often run off with the rainwater and can seep into the ground. And the area’s unique porous limestone doesn’t filter the runoff and ground water well.
Ward compared the mostly limestone landscape, known as karst, to a block of Swiss cheese.
“There’s little holes in Swiss cheese, and naturally, when it rains, there's chemical runoff from farm fields, or really, kind of anything,” Ward said. “If the rain water hits the top of the Earth, goes through the soil — normally it filters out all that stuff. However, if you have Swiss-cheese-hole ground, like we do in our region, the water will funnel into these little crevices and pass through very quickly without getting the proper filtration that it needs to get out those chemical contaminants.”
The Tap-In initiative includes Mower, Dodge, Fillmore, Goodhue, Houston, Olmsted, Rice, Wabasha and Winona counties. The Mower County health department said Mower County has recorded the most samples detecting arsenic and manganese under the Tap-In initiative to date.
Residents of those counties can apply for the program and those who are approved will have a water testing kit sent to their house. They can then simply send back the well water sample for a free analysis. If water is found with high levels of contaminants, well owners can apply for financial assistance for remediation, which can include installation of water-treatment equipment, repairs to the wells or, if necessary, the digging and installation of a new well.
Households with a vulnerable population, including people who are pregnant or families with infants and small children, will be prioritized for the program.
The program was initially started due to concerns that high levels of nitrates were leaching into drinking water. While Ward says the presence of nitrates hasn’t been overly abundant, they have found high levels of other contaminants, including arsenic and lead, which are naturally occurring in the ground.
Ward said lead was the most detected contaminant — found in about 40 percent of the wells tested throughout southeast Minnesota.
