Expert says ‘risk-free drinking water’ doesn’t exist in Iowa, urges well owners to test their water

To a gathering of residents in Dubuque this week, David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa, said there is “no such thing as risk-free water.”

“I would just like to say that when it comes to safe and drinking water, we throw that around, but it means acceptable risk,” Cwiertny said in his Tuesday night talk with the Dubuque Area Land and Water Legacy organization.

The national standard for safe nitrate levels in drinking water has been limited by the U.S. Environmental Protection Agency to 10 milligrams per liter since 1992.

High nitrate levels in drinking water have been linked to several types of cancer, as well as “blue baby syndrome,” a condition that results in discoloration of the skin due to low levels of oxygen in the blood.

Cwiertny said Tuesday it may be time to update the EPA’s thresholds.

“I will say the science, while it can be pretty compelling, has not been enough to shift a standard,” Cwiertny said. “That's why we're sort of caught where we are today, with lots of people in Iowa drinking levels of nitrate that science might say is unsafe, but the standard and the regulations for drinking water are saying is acceptable.”

For example, Cwiertny said research from the National Cancer Institute has linked drinking water nitrate levels of 3 to 5 mg/L to increased risk for bladder, ovarian and thyroid cancers.

Vulnerabilities of northeast Iowa

Cwiertny said parts of northeast Iowa are particularly vulnerable to water infiltration because of the karst terrain found there. Karst is a porous topography that allows surface pollutants to quickly filter into groundwater and streams.

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He said underground aquifers that are highly productive are more vulnerable to contamination, and northeast Iowa private wells are the most vulnerable in the state.

Cwiertny pointed to a petition several advocacy groups in Minnesota filed with the EPA in 2023, urging the government to take action under the federal Safe Drinking Water Act. Ultimately, the EPA sent a letter to the Minnesota Pollution Control Agency and state departments of health and agriculture calling attention to health risks from groundwater nitrate contamination in the state’s karst region.

Several Iowa environmental groups filed a similar petition with the EPA in April 2024, asking the agency to step in to protect northeast Iowa’s drinking water, but as of this spring, no action had been taken.

Cwiertny said he and his team at the Center for Health Effects of Environmental Contamination conducted tests of wells in six counties that have high well density. Those included Black Hawk, Delaware, Jones, Jackson, Clinton and Cedar counties. He said the data, collected between 2016 and 2020, showed that 10 percent of the wells tested above the EPA’s 10 mg/L threshold.

“You might be saying 10 percent, is that a lot? I guarantee you, if 10 percent of public water systems in Iowa were in violation of the nitrate standard, we would be leading the national news every night,” Cwiertny said. “On average, it's like a couple of percents of water systems that have violations in a year. This would be a national travesty, and we let it happen in private wells.”

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Water testing in Dubuque

Allie White, Dubuque County public health director, told the group Tuesday that much of Dubuque County relies on private wells for drinking water.

Unlike public water systems, which are monitored and regulated, the tests of private wells “fall solely on the shoulders of individual homeowners,” White said, adding that navigating water quality issues as an individual can be a “daunting” task.

White said the state-funded Private Well Grants Program can help well owners test their water by offering free test kits so homeowners know the water they are drinking is safe.

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“Through this program, we work to ensure that no matter your ZIP code or income level, that every resident has the opportunity to protect their family's health,” White said. “We're proud to bring these services to Dubuque County and to be part of a statewide effort that's making a real difference, especially in some of our rural communities.”

Over the past three years, White said Dubuque County Public Health has “fully utilized” its annual funding of about $40,000 for well testing. And, she said, the county has secured additional state funds to expand the program.

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“So if other counties across the state don't use their allocation, there's a period where we can say, ‘Hey, we've tested so many wells, and we've expended 95 percent of our funds,’ so then we can get some reallocation to expand the services we offer,” White said.

Cwiertny said northeast Iowa has historically been “heavily engaged” in spending its water quality funds to boost testing in the region.

“Northeast Iowa has long understood that their wells are vulnerable, and the counties have been aggressive,” he said. “The downside is that, unfortunately, Dubuque County has a bit of a rough history where they were not using their funds at the time, under prior leadership. It's great to see that this has been corrected, but Dubuque was one that we actually called out with some of the lowest levels of expenditures historically.”

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues. She is also a contributing writer for the Ag and Water Desk, an independent journalism collaborative focusing on the Mississippi River Basin.

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Comments: olivia.cohen@thegazette.com