EPA says Iowa's 2024 list of impaired waters is incomplete

Federal regulators want the Iowa Department of Natural Resources to expand the state’s 2024 list of impaired waters and is accepting public comment through Dec. 13.

The U.S. Environmental Protection Agency said nitrate and nitrite levels in six sections of the Cedar, Des Moines, Iowa, Raccoon and South Skunk rivers have exceeded safe drinking water standards and need to be curtailed.

With the EPA’s additions, Iowa’s list would include 581 impaired streams, rivers, lakes and reservoirs.

Michael Schmidt, staff attorney for the Iowa Environmental Council, said the EPA’s response stands out.

“[The] EPA does not very often disapprove state submissions for impaired water lists, like this, and I think [the] EPA’s action recognizes the high nitrate concentration across Iowa, especially in Iowa’s major rivers,” Schmidt said. “It’s a demonstration that we are not fully addressing our water quality problems in Iowa.”

A growing number of studies have linked low nitrate concentrations in drinking water to colorectal cancer, thyroid disease and other health issues.

The Iowa Environmental Council criticized the DNR earlier this year for de-listing waters prematurely.

The Iowa DNR said it’s reviewing the EPA’s action and declined further comment.

What does it mean for a waterway to be on the list?

Every two years, the EPA requires states to submit a surface water quality report and a list of every impaired waterbody or segment. The causes for impairment run the gamut, from fish-killing fertilizer spills to E. coli that shuts down beaches.

Once a waterbody or segment is on the list, the state works with the EPA to set a Total Maximum Daily Load, or TMDL. It’s a target to reduce pollutants and a starting point to create a restoration plan.

On Nov. 12, the EPA said it partially approved the Iowa DNR’s submission, including its rationale to delist 84 water segments that had been on the impaired list. But the federal agency disagreed with the state’s decision to leave out half a dozen segments that provide drinking water to Des Moines, Iowa City, Cedar Rapids, Ottumwa and Oskaloosa.

The decision stated, “Iowa is not assessing all pollutants with toxic effects with reasonable consideration of the individual pollutant, endpoints, and adverse effects being considered.”

The EPA said the Iowa DNR did not use all readily available public data “from the Iowa Water Quality Information System, which includes data from the University of Iowa’s Iowa Institute for Hydrologic Research (IIHR) and continuous data from the U.S. Geological Survey; data from local and state entities available through the organization Upper Iowa River; and volunteer data available through the Clean Water Hub.”

The agency said the Iowa DNR did not provide a science-based rationale for excluding some information.

The EPA is accepting public comments on the additions to Iowa’s 2024 impaired water list through Dec. 13, 2024. After reviewing comments, the EPA said it will issue a response and may revise its decision before transmitting the list to the Iowa DNR.