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Mississippi River conservation groups are among a broad coalition urging the federal government to take action against nitrate contamination in drinking water, which they say has reached “crisis levels” and is a public health emergency.

Nitrate, which forms when nitrogen-rich sources combine with oxygen, has long been found in the country’s surface waters and groundwater, where it can end up in people’s drinking water. Consuming water with elevated levels of nitrate is linked to birth defects, thyroid problems and some cancers.

Agricultural fertilizer and manure are the most common sources of nitrogen to groundwater, with septic systems and lawn fertilizers also contributing. An April analysis from the Environmental Working Group found that about 18% of the U.S. population from 2021 to 2023 used drinking water from community systems with 3 milligrams per liter (mg/L) or more of nitrate, the threshold at which the Environmental Protection Agency says indicates contamination.

Advocates say nitrate contamination has struggled to capture public attention but is costly and hazardous to those it affects. 

A May 5 letter to the Department of Health and Human Services and the EPA was signed by 80-plus groups, about a third of which are located in or focused on the Mississippi River basin. It calls on the agencies to “immediately identify and eliminate sources of nitrate pollution in drinking water and provide funds to communities to reduce nitrate to safe levels.”

The letter cites a recent report from the Iowa Environmental Council and the Harkin Institute at Drake University in Des Moines that found high nitrate levels in drinking water, as well as the presence of pesticides and forever chemicals, are linked to rising cancer rates in Iowa. Intensive farming across the state, including corn, soy and hogs, is the dominant source of nitrate pollution, the report notes.

“We understand these are long-term problems,” said Tyler Lobdell, senior attorney at Food & Water Watch, which spearheaded the letter. “The longer we wait to address root causes, the more difficult, and more expensive (it is), and the more harm is caused in the long run.”

The Department of Health and Human Services did not respond to a request for comment on the letter. A spokesperson for the EPA said it is beginning the next round of review of national drinking water regulations, last published in 2024.

Too much nitrogen taints drinking water, hurts river ecosystem

Nitrate contamination is a widespread problem across the country, especially in the Corn Belt, but actions to address it have been slow-going.

Groups in multiple states, including Wisconsin, Minnesota and Iowa, have previously petitioned the EPA to take emergency action on nitrate problems in specific regions. Lobdell said the agency has either ignored or given an insufficient response to those petitions, dating back several years and multiple presidential administrations.

Under former President Joe Biden, the EPA restarted an assessment — which had been suspended during the first Trump administration — of the impacts of nitrate on human health. Environmental advocates had hoped that it could lead to an adjustment of the national standard for nitrate in drinking water, which currently sits at 10 mg/L, because some research shows impacts to human health below that level. Little progress has been made on the assessment.

Beyond human health impacts, too much nitrogen in surface water can drive excessive algae growth, causing harm to fish and other aquatic life. It’s one culprit, in addition to phosphorus, in the creation of the Gulf of Mexico’s “dead zone,” an area of low oxygen that spans thousands of square miles from the mouth of the Mississippi River.

Kelly McGinnis, executive director of the environmental advocacy organization One Mississippi, a signatory on the letter, said that humans aren’t separate from the environment and that addressing nitrate contamination would have positive impacts on both.

She said she hopes the letter catches the attention of Health and Human Services Secretary Robert F. Kennedy Jr., who has pledged to “Make America Healthy Again” and has shown interest in reducing toxins in people’s diets.

“We felt the urgency right now to take advantage of the new research (from Iowa) to say, ‘Hey, this is something you guys need to be addressing,'” McGinnis said.

The spokesperson for the EPA said the agency is “committed to Making America Healthy Again by taking real, tangible steps to evaluate risks of nitrates in drinking water while following the law and gold standard science.”

This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouriin partnership with Report for America, with major funding from the Walton Family Foundation.

Wisconsin Watch is a member of the Ag & Water Desk network. Sign up for our newsletters to get our news straight to your inbox.

Mississippi River groups tell feds to act on nitrate contamination is a post from Wisconsin Watch, a non-profit investigative news site covering Wisconsin since 2009. Please consider making a contribution to support our journalism.

Nearly one-fifth of Americans relied on drinking water systems with elevated and potentially dangerous levels of nitrate in recent years, according to a new study released Thursday.

The nonprofit Environmental Working Group examined test data collected by water systems across the country between 2021 and 2023, the most recent data available. 

Water systems serving more than 3 million people exceeded the federal safety limit of 10 milligrams per liter over the three years, the research and advocacy organization found.

The analysis also found that thousands of water systems serving more than 62 million people reported nitrate levels above 3 milligrams per liter at least once during those years, which indicates human-caused drinking-water contamination. 

Researchers are increasingly questioning whether the federal threshold should be lowered as more studies find links between even low levels of nitrate consumption and cancer and birth defects. Federal law limits nitrate levels in drinking water because of its association with blue-baby syndrome. 

Nitrate is a natural component of soil, but has become a growing problem for drinking water systems because of crop farming’s use of nitrogen fertilizers and runoff of nitrogen-rich manure from livestock operations.

States with big agricultural industries recorded more reports of elevated nitrate levels. In fact, the report found that 64% of all water systems that recorded nitrate levels at or above the legal limit were in just five states: California, Texas, Kansas, Nebraska and Oklahoma. 

But Anne Schechinger, the organization’s senior director of agriculture and climate research who authored the report, said the issue affects urban and rural areas alike.

“A lot of people have this idea that this issue is just a rural issue for small towns near farms. But we found with this analysis that that is not just the case,” she told Stateline. “Based on how watersheds work, you can live very far from a farm and still be drinking water contaminated with nitrate.”

The analysis relies on public records obtained from public drinking water systems in every state except New Hampshire, where data was not provided, she said. In addition to its report, the Environmental Working Group created a map showing community water systems with elevated nitrate levels across the country.

Elevated nitrate levels have befuddled water providers across the country for years. Not only are they expensive to remove from drinking water supplies, but nitrate levels can fluctuate with the seasons as heavy rains can quickly push remnants of fertilizer or manure into streams and rivers. 

Iowa’s largest water provider last year asked residents to refrain from watering lawns, filling pools and washing cars as its nitrate removal system struggled to keep up with elevated levels. 

Des Moines is home to one of the largest nitrate removal systems in the world, which costs about $16,000 per day to operate, officials said. Smaller communities that rely on groundwater have been forced to dig deeper wells, Schechinger said.

Climate change is further fueling the problem: Agriculture is a major driver of greenhouse gas emission. The heavy rainfalls and prolonged droughts from more extreme weather worsen nitrate runoff into lakes, rivers and groundwater. 

“We know those climate conditions are going to make this problem worse,” Schechinger said. “And that’s likely to cost us all more and also (raise) more concerns for our health.”

Stateline reporter Kevin Hardy can be reached at khardy@stateline.org.