Environmental groups urge EPA to restore nitrate impairment designation on Iowa river segments

The Raccoon River near Walnut Woods State Park in West Des Moines on Oct. 2, 2025. (Photo by Cami Koons/Iowa Capital Dispatch)

Environmental groups penned a letter to the U.S. Environmental Protection Agency urging the federal agency to maintain its previously rescinded ruling that seven segments of Iowa rivers were impaired due to nitrate concentrations. 

The environmental groups said EPA’s decision to delist these segments was “inconsistent” with the law, failed to hold polluters accountable and would lead to increased regulatory costs for water treatment in Iowa. 

The decision from EPA followed a summer with near-record high nitrate levels in the Des Moines and Raccoon rivers near Des Moines and the first-ever lawn watering ban from Central Iowa Water Works on account of the high nitrate concentrations, coupled with summer water demand. 

Dani Replogle, staff attorney for the environmental group Food & Water Watch, called the EPA decision “baseless” and said it “does not inspire confidence in the federal agency meant to safeguard clean water and protect our health.” 

“The data is clearer than ever that Iowa waterways are overwhelmed with persistent, toxic nitrate contamination,” Replogle said in a statement. “Iowans need more clean water protections — not less.”

Background 

EPA ruled in January that the Iowa Department of Natural Resources needed to add seven river segments to its 2024 list of impaired water segments. This decision, which EPA said was due to the high levels of nitrate and “nitrate plus nitrite,” another form of combined nitrogen similar to nitrate, in the segments, was rescinded by EPA in July.

EPA said in their letter changing the decision that it is seeking additional information from DNR to determine “whether  ‘good cause’ exists to not include the seven referenced waters.”

The original decision was opposed by DNR, with DNR’s executive director Kayla Lyon arguing the agency was holding Iowa’s department to “a very high standard.” DNR argued the designation would yield higher costs and greater regulatory oversight associated with the designation. 

The impaired segments, on the Cedar, Des Moines, Raccoon, Iowa and South Skunk rivers, serve as drinking water sources for several municipalities including Des Moines, Iowa City and Cedar Rapids. 

EPA holds that concentrations of nitrate and nitrite above 10 milligrams per liter in drinking water can lead to shortness of breath, blue-baby syndrome or even death in infants under the age of 6 months. Other research indicates long-term exposure to nitrate in drinking water is linked to certain types of cancer. 

According to the EPA’s letter from July, announcing the recission of the impaired water segments, DNR did not list the segments in its impaired list because it applied standards for nitrate that “solely protect against chronic effects” while EPA applied standards that apply to both chronic and acute effects of nitrate. 

Per EPA’s letter, this information was made clear in May 2025 when DNR submitted additional information to EPA explaining why the segments do not need an impairment listing. 

Iowa Environmental Council, Environmental Law & Policy Center and Food & Water Watch, the groups that penned the letter to EPA, also obtained records, via a public information request, on communications between DNR and EPA. Per the records request, the documents submitted were DNR’s 2001 water quality standards document and EPA’s subsequent approval of the standards. 

The groups allege these documents, being more than 20 years old, were already submitted to EPA. The environmental groups allege any additional information, including explanation from DNR, occurred in an “undocumented oral conversation” which was referenced in an obtained email. 

The environmental groups, in their letter, argue these actions were “outside the process contemplated” in the Clean Water Act, which allows for a change to impaired water lists when EPA requests additional documents, and for public comment. 

Michael Schmidt, general counsel for Iowa Environmental Council said the decision “lacks transparency” and was “based on outdated” information. 

“EPA’s action undermines the public process defined in federal regulations and limits public transparency,” Schmidt said in a statement.

An EPA spokesperson said in a statement that DNR’s impaired waters list for 2024 made use of data from 2020-2022.

“IDNR is in the process of compiling and assessing water quality data from 2022-2024 and is expected to public notice its draft 2026 list early next year, which will include an assessment of these same seven water segments,” the spokesperson said in an emailed statement. “Concurrently, EPA will be working with IDNR to understand and resolve the issues forming the basis for EPA’s reconsideration of its 2024 decision.”

The spokesperson said it is working with DNR in the “spirit of cooperative federalism” and using “the latest information” to ensure water quality standards are “followed and upheld.”

“EPA has been tracking the levels of nitrate and is ensuring that all of the information and data collected by the cities, universities, and other groups is provided to the Iowa Department of Natural Resources (IDNR) for evaluation,” the spokesperson said.

Acute vs chronic

DNR argued its application of nitrate parameters pertained to chronic effects, which is why the department chose not to list the seven segments. The environmental groups argued the nitrate standard used does not apply solely to chronic effects. 

The letter from environmental groups argued a symptom like blue-baby syndrome is an acute, rather than chronic, health outcome and is prevented by the EPA via the maximum contaminant levels, or MCLs, adopted under the Safe Drinking Water Act. The letter alleges the cited 2001 water quality standards from DNR incorporated these MCLs “as the water quality standard.” 

A spokesperson for DNR declined to comment on the environmental groups’ letter and their position against the department’s reasoning.

In public comments to EPA’s original action, DNR director Lyon said the federal agency’s decision was incorrect because nitrate is not a “toxic pollutant.” The letter countered this argument by saying EPA’s toxic pollutant list outdated. 

The letter said “overlooking the acute consequences” of high nitrate is inconsistent with the Safe Drinking Water Act. 

Environmental groups also cited Iowa Code for water quality standards and argued the “narrative” standards for surface water prohibit “toxic pollutants in toxic amounts.” 

The referenced state standards note that substances toxic to humans, or “detrimental to treatment process” must have limited concentrations in surface water. 

Water treatment facilities are responsible for keeping contaminants, like nitrate, within legal limits for drinking water. In Des Moines, where the Des Moines and Raccoon rivers were both elevated above 10 mg/L for nearly 70 days this summer, water treatment facilities were forced to run costly nitrate removal systems for more than 110 days this summer. 

Environmental groups via the letter, said removing the segments from the impaired list “fails to address the causes” of pollution and “unfairly burdens” water treatment facilities. 

Leadership from Des Moines Water Works echoed this sentiment following EPA’s delisting decision. They said in a news release that the decision did not align with financial and operational realities the utility faced in providing clean drinking water to the city. 

Once a water segment is listed as impaired, EPA and DNR develop water quality improvement plans, known as a Total Maximum Daily Load or TMDLs, that require reductions to the known pollutant. 

“Drinking water issues across the state, from western Iowa to the waters removed from the list by EPA, demonstrate the necessity for further action to address pollution in drinking water sources,” the letter said. 

Iowa Environmental Council Water Program Director Colleen Fowle said EPA’s decision holds that the waterways in question meet safe drinking water standards, which she said is an “unjustified and dangerous” claim. 

“Removing the impairment at the same time Central Iowa had to implement unprecedented water use restrictions made no sense,” Fowle said in the statement. “EPA’s action fails to put the onus on the polluters to adopt practices that will actually fix the problem.” 

The environmental groups called for EPA to restore the impaired waters designation and consider their stated concerns as the agency reevaluates Iowa’s impaired waters list.