The U.S. Environmental Protection Agency (EPA) is maintaining its decision to exclude several Iowa river and stream segments from the state’s impaired waterways list, despite concerns over elevated nitrate levels.
The decision involves portions of the Cedar, Des Moines, Iowa and South Skunk rivers. These waterways have been the subject of concerns related to nitrate contamination, which is commonly associated with agricultural runoff, including fertilizers and livestock waste.
Food & Water Watch and the Iowa Environmental Council filed a lawsuit against the EPA on May 14, 2026, challenging the agency’s decision. The organizations argue that the affected river segments should have been included on the impaired waters list because of repeated instances of elevated nitrate levels.
The EPA has defended its decision, citing its review of available water-quality data and the criteria used to determine whether waterways qualify for the list.
According to Dani Replogle, a staff attorney with Food & Water Watch, the EPA’s reasoning for excluding the waterways does not adequately address the nitrate concerns. Replogle pointed to the agency’s consideration of the number of days for which water-quality data was available.
The Iowa Department of Natural Resources collects and submits water-quality information to the EPA. That information is used to evaluate waterways under the federal Clean Water Act’s Section 303(d) requirements.
The impaired waters list identifies waterways that do not meet applicable water-quality standards. Inclusion can lead to the development of cleanup plans designed to address pollution and improve water quality.
The river segments involved in the dispute are also identified as drinking water sources. Nitrate contamination is a public health concern because elevated exposure has been associated with certain health risks, including birth defects and colorectal cancer.
A report from the Harkin Institute and the Iowa Environmental Council has also examined nitrate pollution and environmental health concerns in Iowa.
The lawsuit remains pending, and the dispute centers on how water-quality data and federal standards should be applied when determining whether Iowa waterways belong on the impaired waters list.
Source: Iowa News Service / Public News Service. Reporting by Mark Moran, Producer.
