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South-central Kansas is sandy. Commodity crops abound. And you don’t have to dig very deep to hit groundwater.
These three seemingly unrelated facts make for a trifecta with an unwanted prize: A lot of the drinking water is now polluted with nitrate, mostly from chemical fertilizer.
Scientists have tested more than 200 private wells across nine counties in this region. About half of the sites turned out to contain more nitrate than the federal government considers safe to drink.
Many of the others were not far from crossing that point.
“In another year or two, you could be above it,” said Matthew Kirk, a geology professor at Kansas State University who’s been busy for the past five years helping families in this region find out what’s in their water — and simultaneously piecing together a picture of how widespread the contamination has become.
Across the Midwest and Great Plains, large-scale fertilizer application and livestock facilities have upped the pace of nitrate accumulating in groundwater.
In parts of the region, many private wells that rural households relied on for decades are no longer safe to drink from without installing pricey treatment.
In Kansas, communities are discussing how to fertilize crops more carefully. In Iowa, economists are trying to pin down the costs of polluted groundwater. In Minnesota, well owners and environmental groups are suing for stricter fertilizer and manure regulations.
Meanwhile, some researchers worry that families often don’t know that their water has changed over time, and now poses a serious health risk.
“Most of the families are just — from generation to generation — using the same well,” said Kansas State graduate student Thisura Ilukgoda Gedara, who helped sample wells for free for farmers, ranchers and others in the area. “ We can help them to understand whether the water that they are consuming is good or bad.”
Some aquifers are especially vulnerable
Nitrate pollution has hit risky levels faster in some parts of the country than others.
It’s not that these places are the only ones spraying chemical fertilizer on crops or concentrating animals on feedlots. But accidents of local geology allow the nitrogen produced by these activities to more quickly penetrate the groundwater there.
In south-central Kansas, nitrogen easily seeps into the Great Bend Prairie Aquifer because its water is often just tens of feet below ground and the sandy soil is particularly permeable.
In southeast Minnesota, highly penetrable, fractured bedrock gives the nitrate easy access, as do the many spots where surface and groundwater connect.
Such contamination has repercussions for human health.
The U.S. Environmental Protection Agency has for decades considered 10 milligrams per liter of water to be the safety limit for nitrate in public water supplies. This is based on evidence that higher amounts can cause a dangerous condition in infants — methemoglobinemia. Also known as blue baby syndrome, this can be fatal.
But some public health researchers remain concerned that unnaturally high amounts of nitrate in drinking water might play a role in other conditions, too, such as thyroid disease or colorectal cancer. And they aren’t convinced the EPA’s 10-milligram limit is low enough.
Meanwhile, since the 1990s, more water utilities have been blowing past the EPA’s limit – in particular, those that depend on groundwater instead of lakes or rivers.
In Texas alone, at least 50 community water systems tested above the EPA limit in 2022 and 2023, affecting the water supplies for 45,000 people.
The city of Pratt, in south-central Kansas, had to shut off two wells that comprised nearly a quarter of its total water supply. The town of just 6,500 people must now figure out how to afford infrastructure to treat the water, which is expected to cost tens of millions of dollars.
Because they are regulated, public water suppliers monitor nitrate levels and have to protect their customers from this contamination. But more than 40 million Americans get their drinking water from private wells, and it’s not clear how many test their well water for pollutants.
A survey of rural households in parts of Iowa with known nitrogen pollution found in 2022 that 10% of respondents had tested their water in the past year.
The Centers for Disease Control and Prevention urges well owners to test annually. Nitrate levels can change that fast, and the contamination doesn’t make itself known in any obvious way.
“There’s no smell, there’s no color,” said Kirk, the Kansas State geologist. “If you have high nitrate, it looks and tastes fine potentially.”
The price of groundwater pollution
Installing equipment to remove nitrate can cost a household hundreds or thousands of dollars, depending on the treatment system and how comprehensive it is.
“Brita filters aren’t going to do it,” said Gabriel Lade, an economist at the Ohio State University.
Lade is one of the researchers behind the 2022 Iowa study. His expertise is environmental and agricultural economics.
A decade ago, while at Iowa State University, he and some colleagues set about documenting the economic benefits for Iowa of reducing nutrient pollution, which includes nitrate. Lade said the information could help policymakers weigh how much money to spend on conservation practices that help mitigate nutrient pollution, such as wetland restoration.
To tally the potential benefits of less pollution, economists worked on understanding the pollution’s toll on Iowa. For example, nitrogen and phosphorus accumulates in lakes, fueling toxic algae blooms.
“People tend to change where they recreate,” Lade said, “And there’s a cost to that.”
The researchers found that reducing this nutrient load in lakes could translate to $30 million in recreational benefits for Iowans.
Another example is when elevated contamination pushes water utilities to spend millions of dollars on removing nutrients from drinking water to protect public health.
Iowa’s most high-profile example of this is in Des Moines, which has worked to combat nitrate in its drinking water for years. The city’s water utility sued upstream agricultural areas in court. The case was dismissed.
Iowa State researchers also noted that nutrient pollution impacts rural families that depend on private wells instead of utilities. Only, they ran into hurdles pinning down the extent of the impact.
No one knows, for example, how many Iowans are drinking untreated, nitrate-laden wellwater. This makes it difficult to explore the cost to human health.
“This is one of the biggest challenges,” Lade said. “It’s really hard to tell what exposure is.”
This sent Lade and his colleagues down a different path: Surveying people who depend on wells. The researchers mailed surveys to rural households in counties with known nitrate problems and more than 8,000 private well users replied.
About 40% said they drink their well water without filtering it and without having tested it in the past year.
Many respondents believed nitrate can be a cause for concern. But they were more likely to think it was a problem somewhere else in Iowa than specifically in their area.
“ It may relate to just basic human biases,” Lade said. People may think, “‘I know it’s an issue, but my water looks clear, smells fine. We’re probably good to go.’”
Lade and his colleagues have now secured funding to expand their research in Iowa by surveying households in more counties and potentially giving them information tailored to shed light on the nitrate situation in their specific area.
Iowa funds counties to test households’ well water for free. However, University of Iowa researchers found in 2019 that most counties weren’t using up the money for tests because not enough people were requesting them.
A more informed public
Nitrogen pollution has many sources, including livestock facilities, wastewater treatment plants and spreading manure on fields. Individual wells can even become contaminated from being located near a septic tank.
In south-central Kansas, chemical analysis indicates most of the nitrate in the region’s aquifer comes from synthetic fertilizer applied to cropland, said Kirk, the Kansas State geologist.
The increases in nitrate over the past four decades in this region rank as some of the biggest nationally compared to data gathered in a national long-term study, he said.
Kansas State scientists found one well with more than five times as much nitrate as the EPA considers safe to drink.
The university has been sampling wells for free the past five years. Many rural households found out that their water was unsafe to drink without treatment.
Kirk hopes word will spread among relatives and neighbors, prompting others to test their water, too. His team also gave public presentations in the region to show residents what they were finding.
At a recent workshop, Kirk said, farmers, Kansas State Extension agents, water managers, scientists and others gathered to discuss the problem.
Participants talked about ways to get more precise with fertilizer or to reduce how much they need. For example, they spoke about improving the soil by planting cover crops or applying fertilizer only when and where crops will use it. Overapplying or applying at the wrong time makes it more likely that nitrogen will escape into the groundwater.
Meanwhile, Kirk co-published a guide for Kansas farmers who irrigate. In areas with high nitrate levels in the groundwater, irrigation is now effectively a source of fertilizer.
“You can account for that and basically buy less fertilizer,” he said. “That’s going to decrease your nitrogen input … and save you money.”
The legal battle in Minnesota
Nitrate contamination has led to lawsuits in some states.
In southeast Minnesota, private well owners, environmentalists and trout conservationists accuse state agencies of falling down on the job while nitrate surges in groundwater, rivers and streams.
In 2023, they petitioned the EPA to take emergency action to protect public health. The EPA told Minnesota to take “timely actions” to address the pollution, to make sure people know about the hazard, to help them test their well water and to offer bottled water where wells prove to be contaminated.
Minnesota state agencies told the EPA they would tackle the most immediate matters first — such as making sure households had bottled water where needed — and review and update rules related to sources of nitrate pollution in the long term.
But those who originally petitioned the EPA are unimpressed with the state’s efforts.
Last year, three of the groups — the Minnesota Center for Environmental Advocacy, the Minnesota Well Owners Organization and Minnesota Trout Unlimited — sued the Minnesota Department of Agriculture and the Minnesota Pollution Control Agency in state court. They argued the agencies’ regulation of feedlots and farms is far too weak.
A judge ordered the agencies to gather public feedback on how they currently regulate manure and fertilizer. The Pollution Control Agency has started work toward updating its regulations for the state’s 17,000 feedlots.
Agriculture groups disagree with the push for stronger rules. Nine groups filed to intervene in state court last year, including the Minnesota Corn Growers Association, Minnesota Milk Producers Association and Minnesota Soybean Growers Association.
“Minnesota has some of the strictest water protection rules in the country,” the 7,000-member Minnesota Corn Growers Association wrote in a news release. “Farmer organizations and individual farmers share the goal with the public of protecting our water.”
The groups are arguing that the lawsuit risks undermining the integrity of the state’s regulatory process.
“Rules should be based on ‘sound/accepted science’ and not political positions and the PR claims of advocacy organizations,” the news release said.
But supporters of tighter regulation say they want Minnesota to figure out what truly effective regulation looks like, even if it ends up requiring a significant rewrite.
“That’s the fight we’re looking for,” said Paul Wotzka, co-founder of the Minnesota Well Owners Organization and a resident of rural southeast Minnesota with a private well. “We think the existing rules stink and you’ve got to kind of tear down what is there before you can build anew.”
Wotzka is a water quality expert who spent decades working for the Minnesota Department of Agriculture and other state and local agencies. That work included monitoring pollution in streams, which in southeast Minnesota easily ends up in the groundwater, too.
He believed it must be possible to farm without polluting water and ultimately decided to try. So he and his wife became organic farmers. They grow about 16 acres of vegetables, fruits and nuts, from asparagus and rhubarb to peaches and hazelnuts in Wabasha County.
During their three decades on the farm, Wotzka said the nitrate concentration in their well has dropped 80%. He credits two changes for the decrease: The state reverted nearby cropland to forest, and he farms without chemical fertilizer.
“That’s a success story,” he said. “There is hope.”
Still, Wotzka worries state regulators don’t have much appetite to challenge the status quo approach to farming that relies heavily on fertilizer.
“ Big Ag would like you to believe that there are no alternatives to what you need to do to grow corn and beans,” he said. “People have to start looking at alternatives.”
He’d like to see more discussion of environmentally friendly approaches.
Half a century ago, agriculture in southeast Minnesota looked far different from today, he said. Many more farmers owned pasture and hayfields. They rotated alfalfa and small grains onto their fields, helping the soil.
In recent decades, corn and soybean acres have surged, federal policies steer farmers toward monocropping, and conservation programs remain too rigid for farmers who might otherwise take a very different approach in hopes of growing food while keeping water clean.
“It’s really easy for people to say, ‘Well, they’re going to give me subsidized crop insurance for corn and soybeans,’” Wotzka said. “‘Why would I grow anything else?’”
Celia Llopis-Jepsen is an environment reporter for Harvest Public Media and host of the environmental podcast Up From Dust. You can follow her on Bluesky or email her at celia (at) kcur (dot) org.
Harvest Public Media is a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
