A bill that advanced in a House subcommittee and committee Tuesday would prohibit a water segment from being designated as impaired unless the Iowa Department of Natural Resources identified the percentage of fecal bacteria coming from each animal species that contributed to its impairment.
Every two years, the DNR must submit a list to the U.S. Environmental Protection Agency of water segments in the state that are “impaired” or don’t meet water quality standards.
Once listed, DNR and the EPA work to develop an improvement plan that puts limitations on the amount of pollutants that identified polluters can discharge into the surface water segments.
Iowa’s most recent list, submitted in 2024, tagged more than 700 water segments as impaired, but the EPA initially rejected the list and asked the state to add seven additional river segments that were impaired with high levels of nitrate.
The Biden-era decision to add the additional segments was rescinded in July 2025 by the Trump administration. Environmental groups announced Tuesday their intent to sue EPA over the removal of the additional segments.
Identifying the contributing animals
HSB 657 would prohibit DNR from placing a body of water on the impaired waters list due to high levels of fecal indicator bacteria, unless the department is able to designate the percentage of each animal species that has contributed to the bacteria amount.
Opponents of the bill argued that it would make it more difficult for DNR to put segments on the impaired list, that it would be cost prohibitive and that the science needed for the analysis is not available.
Republican lawmakers who voted to pass the bill from subcommittee and from the House Agriculture Committee Tuesday, said it was beneficial to have more information about the impaired waters.
Rep. Heather Hora, R-Washington, speaking in committee on the bill, said DNR does have the technology to determine the perpetrating animals and that it “comes down to transparency.”
“As a livestock producer, I believe that it is to our benefit, when they put out these reports of impaired waters, that we actually know who’s impairing the water,” Hora said.
Jason Palmer, speaking on behalf of the DNR, which was registered undecided on the bill, said the department currently conducts some microbial source tracking at state park beaches that allows it to see if the water has DNA attributable to bovine, swine, geese, humans or dogs.
Palmer said this process doesn’t show the department how much of the fecal indicator bacteria came from different sources.
“You can take those pieces of information together and start to build a picture of different sources that might be present in a water body,” Palmer said. “… But what you can’t do is attribute a percentage or a breakdown of the amount of the actual fecal indicator bacteria that we’re concerned with in the waterway that comes from those different sources.”
In addition to DNR, several groups including Des Moines Water Works, the Izaak Walton League of America and Humane World for Animals also registered undecided on the bill.
Threase Harms read a statement from Des Moines Water Works CEO Amy Kahler, who also said the available science “cannot reliably” assign a percentage breakdown of each species contributing to fecal bacteria.
“Meeting this requirement would also be cost prohibitive,” Harms read from the statement. “Species-level source tracking would require repeated sampling across seasons and flow conditions, specialized laboratory analysis and extensive quality controls.”
Colleen Fowle the water program manager with the Iowa Environmental Council, said the bill would cause the department to “significantly undercount” impaired waters and would increase public health risks. Additionally, she worried the bill would cause the state to be out of compliance with the federal Clean Water Act.
“We do not need to know the species of animal to determine whether bacteria levels pose an immediate health risk,” Fowle said.
Rep. Megan Srinivas, D-Des Moines, who sat on the subcommittee for the bill, said the bill could be “really dangerous” from a public health standpoint. She voted against the bill in subcommittee and in committee.
The bill advanced from committee with a vote of 15-8.
Environmental groups to sue EPA over Iowa impaired water
Food & Water Watch and the Iowa Environmental Council filed a notice of intent to sue the EPA over its decision to remove seven Iowa river segments from the state’s list of impaired waters.
The groups sent a letter to EPA in October, asking the agency to restore the nitrate impairment designation on the rivers.
The impaired rivers included multiple sections of the Des Moines and Raccoon rivers, which are used as drinking water sources for the Des Moines metropolitan area.
Des Moines Water Works opposed EPA’s decision to strip the impaired designation from these segments and said the continued, high nitrate levels in the river make it difficult and expensive for the utility to provide safe drinking water to the metro area.
The utility’s regional authority, Central Iowa Water Works, issued a lawn watering ban for the region over the summer due to the high nitrate levels in the rivers. The utility had to turn on its nitrate removal system in January to keep drinking water concentrations within federal limits as the concentrations in the rivers remained high.
The lawn watering ban, the initial EPA decision to add the segments and a Polk County commissioned study about water quality around Des Moines, have brought water quality concerns to the forefront for many Iowans across the state.
Water pollution is also often linked with the state’s high cancer rates as emerging studies indicate a connection between nitrate exposure in drinking water and certain cancers.
Iowa Environmental Council’s General Counsel Michael Schmidt noted the state’s “ongoing cancer crisis” in a news release from the council on the decision to sue the EPA.
“We have to acknowledge the causes and develop policies to solve them,” Schmidt said. “Trying to sweep them under the rug means Iowa families — both urban and rural — will keep paying with our health and our economic wellbeing.”
Dani Replogle, the staff attorney with Food & Water Watch, said the EPA is “shielding” agricultural industry profits “at the expense of public health.”
“These dangerous rollbacks have to stop — EPA must re-list Iowa’s impaired waterways or we’ll see them in court,” Replogle said.
Cami Koons covers agriculture and the environment for Iowa Capital Dispatch, where this story first appeared.
