Officials from Des Moines Water Works said Thursday a decision from the U.S. Environmental Protection Agency pertaining to water quality did “not align” with the “operational and financial” challenges the utility has faced in providing safe drinking water to Iowans.
EPA previously designated seven river segments, including two connected to Des Moines’ source waters, as impaired segments due to high concentrations of nitrates. The agency rescinded the decision in July following pushback from the Iowa Department of Natural Resources on the decision.
Amy Kahler, the CEO and general manager of Des Moines Water Works, said in a news release the high nitrate levels in the Des Moines and Raccoon rivers are making it “increasingly difficult to treat source water.”
“The Des Moines and Raccoon rivers must have targeted water quality plans to be sustainable sources of drinking water for generations,” Kahler said in the release.
State agencies are required to assess surface water quality every two years and develop a list of impaired water segments. These segments have identified pollutants that exceed EPA standards and are given water improvement plans to reduce the pollutants.
EPA rejected part of DNR’s 2025 list to add the seven additional segments in November. The agency finalized the decision in January following a public comment period in which DNR officials pushed back on the ruling, saying in a letter that nitrate was not on the list of toxic pollutants under the Clean Water Act and that EPA did not provide reasoning for the decision.
This summer, Des Moines Water Works and its regional authority, Central Iowa Water Works, banned lawn watering for about a month and half in order to keep the nitrate levels in finished water below safe drinking water standards.
Des Moines Water Works has been running its nitrate removal system, which is estimated to cost about $16,000 per day, for more than 110 days this summer.
“The impairment of the Raccoon and Des Moines rivers threatens our mission and ability to safely [provide] drinking water on behalf of the region to 600,000 central Iowans,” Kahler said.
According to the EPA Region 7 letter sent to DNR in July, DNR submitted additional information to the federal agency in May as to why the state did not list the seven segments identified by EPA.
EPA said in the letter it had evaluated different standards from DNR’s evaluation and would therefore rescind the previous designation on the seven segments in order to “further evaluate this rationale” and reconsider the decision.
Andrea Boulton, chair of the Des Moines Water Works Board of Trustees, said “human health and safety are our top priority.”
“We cannot lose sight of that amid a disagreement on technical language,” Boulton said in the release. “We clearly have a problem in the state of Iowa when water quality issues prevent our drinking water utilities from being able to make clean, safe water for Iowans.”
The release from the utility also pointed to a recent study, commissioned by Polk County, that evaluated water quality issues in the rivers. It said the report “confirmed what Des Moines Water Works has shared for years — nitrate concentrations in the Des Moines and Raccoon rivers are increasing.”
Des Moines Water Works is not the only group concerned about water quality. Citizen groups and environmental groups, including Iowa Environmental Council have also been outspoken about disapproval with the EPA’s decision.
Colleen Fowle, the water program director with Iowa Environmental Council, said this summer “provided a clear picture of the consequences of high nitrate in our drinking water sources.”
“Iowans across the state have been concerned about nitrate in drinking water on all the rivers that EPA has decided to remove from the impaired waters list,” Fowle said in a statement. “All have regularly exceeded the drinking water standard, but not all the cities relying on them have treatment systems to remove nitrate.”
The other river segments were on the Cedar River, Iowa River and the South Skunk River.
Fowle said DNR’s evaluation of the impairments looked at a “short-term” measure, rather than long-term data.
“Looking at only a few years makes no sense for pollutants that can differ from year to year based on streamflow,” Fowle said. “The long-term data show that safe drinking water is at risk. That is precisely what the water quality standard is meant to protect and the reason why these waters need to be listed as impaired.”
Iowa Environmental Council’s General Counsel Michael Schmidt said called the rescission “unprecedented” and “misguided.”
“We call on EPA and DNR to engage in a public process and bring Iowans together to address nitrate concerns that threaten the health and economic wellbeing of people across Iowa, rather than taking action behind closed doors,” Schmidt said.
DNR declined to comment on the decision.
Cami Koons covers agriculture and the environment for Iowa Capital Dispatch, where this story first appeared.
