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Iowa DNR Starts Testing For Manganese In Public Water Systems

Courtesy of CDC
Even though state and federal governments don't regulate manganese in drinking water, the Iowa DNR has begun testing for it.

State environmental officials have started testing the state’s public water supply systems for an emerging chemical of concern.

The metal manganese can contaminate drinking water, but has no federal or state health regulations in place. The mineral naturally occurs in groundwater, surface water and soil. It’s also an essential nutrient for people, which is found in foods like nuts and seeds, and is considered to benefit bone health.

Too much exposure to high levels of manganese, though, according to the Iowa Department of Public Health, could damage a person's nervous system. A person could experience tremors, shaking and an unsteady gait, which Iowa DPH says is more common in the elderly who have been exposed to manganese for longer. 

As of July 1, Iowa’s Department of Natural Resources started collecting water samples from each of the state’s roughly 1,840 public water supply systems. They’ll send the samples to the State Hygienic Lab for testing, said Corey McCoid, a water supply operations supervisor with the Iowa DNR.

“And based on that, we’ll utilize a flow chart that kind of walks us through what additional self-monitoring we’ll require at the public water supply, and what additional testing we’ll require,” McCoid said.

The manganese sampling lines up with a water system’s sanitary survey, a big look at a water treatment plant that happens about every three years. Since testing began, the DNR has entered five samples in its database related to manganese sampling and inspection.

A sixth sample in the database turned up with high levels of manganese, McCoid said, but that sample was related to a water main break, not the inspection. 

The U.S. Environmental Protection Agency has been testing for manganese as part of an effort to study 30 contaminants between 2018 to 2020, known as the agency’s Fourth Unregulated Contaminant Monitoring Rule, or UCMR 4. Under the Safe Drinking Water Act, EPA needs to issue a new list of up to 30 unregulated contaminants every five years that public water systems are tested for.

Around the time the UCMR 4 started, the Iowa DNR assembled a working group of four staff members to study manganese because “we knew this would be an issue in the state,” McCoid said.

Iowa’s Department of Public Health has also been working with the DNR to research the metal’s toxicology, according to an Iowa DPH spokeswoman.

Manganese has a health advisory, which is a recommendation, not an enforceable standard. The U.S. Environmental Protection Agency advises that people avoid drinking their water for more than 10 days in a year if manganese is at or above 1 milligram per liter. For infants younger than 6 months, that advisory is .3 milligrams per liter. Iowa follows the EPA’s recommendations.

McCoid said if they find levels that exceed the EPA’s advisory, they’ll put out a public notice informing the community about the manganese levels and telling people what to do.

As for if there are any clues right now into how widespread problems with manganese are across Iowa, McCoid said, “No, not at this time.” According to a news release from the DNR, groundwater aquifers in western Iowa tend to have higher levels of manganese than other parts of the state.

The Iowa DNR’s testing will take three years and will help the agency see the extent of the problem across the state. The state is doing its own testing while the EPA is researching if national regulation is needed for manganese. McCoid said 60 water supplies in Iowa are part of the EPA’s study.

David Cwiertny, a University of Iowa professor of civil and environmental engineering and the director of the Center for Health Effects of Environmental Contamination, says Iowa is doing the right thing by being proactive and doing testing on its own while the EPA conducts its study.

“There might be some communities that are more vulnerable than others,” Cwiertny said. “It will depend on your source water. Groundwater tends to be more affected by the presence of manganese because that’s the source of it, it’s naturally occurring. All of that makes it very difficult, then, to set a fixed standard for an entire country.”

It's unknown at this point whether new regulations will come from the UCMR 4. Cwiertny said in a text message that the challenge is “no matter what UCMR shows we will still be years away from regulation at [the] federal level.”

“Since 1996 when we’ve gone to this new process with the UCMR, we’ve been unable to really get new regulations on the books,” Cwiertny later elaborated.

When the EPA considers regulating a contaminant, it looks at three criteria: if the contaminant may affect health, if there’s a large chance it will be present in a public water system often enough to cause a health concern, and if regulation “presents a meaningful opportunity for health risk reductions for persons served by public water systems.”

“It’s sort of poorly defined, undefined, what a ‘meaningful opportunity’ means,” Cwiertny said.

Reporting for this story was supported, in part, by a fellowship from the Institute for Journalism and Natural Resources. 

Katie Peikes was a reporter for Iowa Public Radio from 2018 to 2023. She joined IPR as its first-ever Western Iowa reporter, and then served as the agricultural reporter.