Tolkkinen: Southeast Minnesota, it’s past time to purify your well water

If you live in southeastern Minnesota, did you happen to get a letter from the Minnesota Department of Agriculture last May?

If you did, did you open it?

The state sent out 1,186 letters in May to residents of Dodge, Fillmore, Goodhue, Houston, Mower, Olmsted, Wabasha and Winona counties, and only heard back from about 320 of you.

If you got a letter, that means the nitrate level in your well water is too high. The state was offering to purify your water for free or at a reduced cost, especially if you’re pregnant or if you have an infant in your home. They’re starting to install treatment systems in October.

Even a tiny amount of nitrate in drinking water can prevent a baby from absorbing oxygen, a condition called “blue baby syndrome.” Scientists are starting to discover risks for adults, too, such as faster heart rate and nausea. Some studies have found a connection with higher cancer rates, especially gastric cancer, according to the Minnesota Department of Health, but scientists just don’t know enough yet to understand that connection.

The southeastern counties are by no means the only region of Minnesota where wells contain harmful nitrate levels. Wells in southwest and central Minnesota are also at risk. But in 2023, environmental groups asked the U.S. EPA to intervene in the southeastern region, calling nitrate an “imminent” danger to human health given the region’s unique geology. In several townships, more than four out of 10 private wells tested positive for nitrates.

Last spring, the Legislature allocated funding for 800 to 1000 reverse osmosis systems in southeastern Minnesota as part of a $16 million package to address contaminated wells.

Some homes with high nitrate levels have already installed treatment systems on their own, said Margaret Wagner, in charge of pesticide and fertilizer management with the Minnesota Department of Agriculture, which has contracted with Olmsted County to administer the grant for the eight counties.

Keep in mind that the letters went out to people who were concerned enough and had the ability to get their water tested. There remain thousands of untested wells in southern Minnesota, and presumably, hundreds or thousands of people who have no idea that they are drinking water with harmful levels of nitrate.

Now, reverse osmosis and other treatment systems don’t solve the problem of nitrate for the environment. The filters simply remove them from the household drinking water and they exit the house via wastewater to eventually re-enter the environment.

That’s why environmental groups would rather stop nitrate from polluting groundwater in the first place, a tough sell in rural Minnesota, where nitrate-containing fertilizer helps corn grow at ever-increasing densities. Depending on the soil, corn needs 200-250 pounds of nitrogen per acre, some of which gets washed down into the groundwater by rain or irrigation.

Still, changing farming practices can work. Paul Wotzka, a hydrologist and organic farmer who lives on 72 acres in the southeastern part of the state, said the nitrate level in his well actually dropped after they switched to growing organic crops. It was never above the unsafe threshold, but it was close. In 30 years of no pesticides and commercial fertilizer, the nitrogen level has dropped from between 6 and 7 milligrams per liter to 1.2 milligrams.

Wotzka’s property is unique in that he has a shallow well, so it draws from a shallow aquifer and not the deeper aquifers contaminated by farm runoff. He also borders a wildlife management area. He feeds his fruits and vegetables with compost instead of commercial fertilizer.

“What everybody that has an old shallow well should shoot for, is they should start improving their land-use practices so that shallow aquifer can improve in water quality,” Wotzka said.

After hearing his figures, it’s hard to argue with him.

Meanwhile, everybody who drinks from a well should regularly test the water for nitrate. Wotzka is a board member for the Minnesota Well Owners Organization, which offers testing in several counties. Soil and water conservation districts sometimes offer testing at the county level, and private labs also work.

And the state might want to ramp up its outreach. Several people I contacted in southeastern Minnesota, including two township clerks and Wotzka, who follows the nitrate issue pretty closely, hadn’t heard that the state was giving away reverse osmosis systems.

Those who received offers in May to receive free water treatment centers can still submit application forms requesting the reverse osmosis systems. If they don’t have their forms, they can contact hydrologist Nikol Ross at the Minnesota Department of Agriculture, 651-201-6443.

The state will begin reaching out to other well users in southeastern Minnesota later this year or early in 2025.

Karen Tolkkinen is a Star Tribune columnist focusing on the people and issues of greater Minnesota.