‘Black eye’ for Iowa over nitrate in rivers, but experts predict little change

The U.S. Environmental Protection Agency recently added segments of five rivers near large Iowa cities including Cedar Rapids to the state's impaired waters list for nitrate — over the repeated objections of state officials.

That will require the Iowa Department of Natural Resources to evaluate their sources of nitrate contamination — which threatens public drinking water — and develop plans to reduce it.

But those plans can have little effect.

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One such plan for the Cedar River made about two decades ago noted that an estimated 86 percent of nitrate contamination came from agriculture, yet state officials cannot force farmers to do much about it.

The result has been limited projects to cut some of the pollution voluntarily, with little impact on the overall upward trend of nitrate concentrations.

Water quality experts say similar results should be expected from the new round of EPA requirements. At most, they might force the state to publicly acknowledge that farm pollution is a primary threat to the drinking water of hundreds of thousands of people, the experts say.

"This is mostly just a black eye for Iowa," said David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa.

The pushback

In November, the EPA indicated — after months of consideration — it would add six segments of five rivers to the state's impaired waters list for nitrate:

The federal agency said high nitrate concentrations cannot be ignored merely because they happen only periodically. Those concentrations often spike when rainfall percolates through nitrate-laden farm fields into expansive networks of underground drainage tubes, which then empty into streams.

That tiling enables farmers to grow crops in areas that otherwise might be too wet, but they are also a conduit for expedited river pollution.

In 2022, the EPA foreshadowed its recent decision when it warned "the Iowa DNR should assess nitrate as a toxic." That was part of the EPA’s review of the state's impaired water list that year, which happens every two years. There are hundreds of stream segments on the list.

The Iowa DNR has questioned why the EPA appears to have shifted its standard for reviewing whether a stream is impaired by nitrate. The state department historically had used a "10 percent rule" to decide if there is an impairment — when nitrate concentrations exceed the EPA's health limit more than 10 percent of the time.

The EPA claims its addition of the stream segments — which it finalized last month — "did not establish new water quality standards or impose additional assessment requirements on the state."

The Iowa DNR, in a December letter, touted the state's "near-perfect compliance rate of 99.6 percent" for nitrate contamination among the water supplies it regulates, and questioned why the EPA decided to recently consider nitrate a "toxic" contaminant for Iowa water when the agency apparently hadn't for more than two decades.

"Ultimately, the goal of both the EPA and DNR is the same: to ensure that Iowa's surface drinking water sources meet water quality standards so that, in turn Iowa's tap water is safe to drink," Kayla Lyon, the Iowa DNR's director, wrote in December. "It is safe."

Lyon alleged that the EPA's decision violates federal law and "is holding Iowa to a very high standard that it does not enforce elsewhere."

The Iowa DNR was joined by the Iowa Farm Bureau Federation and The Fertilizer Institute in disputing the new impaired waters listings.

What now?

The Iowa DNR declined to comment for this article.

It's unclear whether the new administration of President Donald Trump will reverse the EPA's stance on Iowa's impaired waters list.

The federal Clean Water Act does not set deadlines for states to formulate the total maximum daily load plans it requires for stream segments on that list, said Michael Schmidt, an attorney for the Iowa Environmental Council.

That has spawned litigation in the past when a state has been slow to create the plans, he said, but it's unlikely other lawsuits are possible to force polluters to reduce their nitrate dispersals.

The Iowa DNR can set pollution limits on "point" sources such as wastewater treatment facilities. Those account for about 9 percent of the nitrate pollution in the Cedar River, the state found in 2006.

"We do have significant nitrate concerns in the state, and this is a way to highlight that," Schmidt said of the additions to the impaired waters list.

Rivers across the state had considerable nitrate concentrations last year amid a wet spring and early summer.

The treated drinking water in Cedar Rapids — which is sourced from shallow wells near the Cedar River, not directly from the river — had nitrate concentrations that peaked at about 9 parts per million last year, shy of the 10 parts per million maximum stipulated by the EPA.

Des Moines wasn't so fortunate. Facing periods of high nitrate in the Des Moines and Raccoon rivers — the primary sources of drinking water for the metro area — Des Moines Water Works operated its nitrate removal system for 68 days last year, said Melissa Walker, a spokesperson for the water utility.

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That is the second-most number of days the system has been active in a year, she said, and it cost about $625,000 to operate.

Cedar Rapids and the vast majority of cities in Iowa do not have a similar system.

Comments: (319) 368-8541; jared.strong@thegazette.com