How Fertilizer Use Is Poisoning Farm Country’s Water Supplies | Civil Eats

Across Farm Country, Fertilizer Pollution Impacts Not Just Health, but Water Costs, Too

Overuse of fertilizer means nitrates are on the rise in water supplies, and rural areas bear the brunt.

An Illinois farmer fertilizes a field before planting. (Photo credit: Scott Olson, Getty Images)

An Illinois farmer fertilizes a field before planting. (Photo credit: Scott Olson, Getty Images)

When Jeff Broberg and his wife, Erica, moved to their 170-acre bean and grain farm in Winona, Minnesota in 1986, their well water measured at 8.6 ppm for nitrates. These nitrogen-based compounds, common in agricultural runoff, are linked to multiple cancers and health issues for those exposed. Each year, the measurement in their water kept creeping up.

In the late 1990s, Broberg decided it was time to source from elsewhere. He began hauling eight one-gallon jugs and two five-gallon jugs from his friend Mike’s house. That was his drinking water for the week.

Six years ago, Broberg said, he was “getting too old to haul that water in the middle of the winter.” So, he installed his own reverse-osmosis water filtration system. The measurement of nitrates in his well has now reached up to 22 ppm. Post-filtration, the levels are almost nonexistent.

Broberg, a retired geologist, has committed what he calls his “encore career” to advocating for clean water in Minnesota. He only leases out around 40 percent of his tillable land and has retired much of the rest due to groundwater pollution concerns. Almost one year ago, a group he co-founded, the Minnesota Well Owners Organization, joined other groups to petition the U.S. Environmental Protection Agency (EPA) to address groundwater contamination in southeast Minnesota.

The EPA agreed, stating that “further action is needed to protect public health” and requested that the state create a plan for testing, education and supplying alternative drinking water to those most affected. Advocates in Wisconsin filed a petition, too. Last month, 13 separate groups in Iowa did the same.

This advocacy comes in light of increased regional attention on nitrate pollution and its health effects. In Nebraska, researchers have connected high birth defect rates with exposure to water contaminated with nitrates. In Wisconsin, experts warn that exposure to nitrates can increase the risk of colon cancer.

Access to clean water, as defined by the United Nations, is a human right. And yet many currently don’t have that right, even in a country where potable water is taken for granted. What’s more, the cost of clean water falls more heavily on less populated areas, where fewer residents shoulder the bill. A report by the Union of Concerned Scientists concluded that the cost for rural Iowa residents—who often live in areas with smaller, more expensive water systems—could be as much as $4,960 more per person per year to filter out nitrates from their water than their counterparts in cities like Des Moines. Nitrates are affecting water utilities from California to D.C., and the reason comes down to one major source: Agricultural runoff.

Where The Trouble Begins: ‘A Leaky System’

The root of water-quality issues in the Midwest starts with its cropland drainage system, a network of underground, cylindrical tiles that drain excess water and nutrients from the land and funnel it downstream. Those tiles, which were first installed in the mid-1800s and have now largely been replaced with plastic pipes, ultimately allowed farmers to grow crops on land that was once too wet to farm.

Lee Tesdell is the fifth generation to own his family’s 80-acre farm in Polk County, Iowa. Tesdell explained that when his European ancestors settled in the Midwest, they plowed the prairie and switched from deeply rooted perennial plants to shallow-rooted annual crops like wheat, oats, and corn instead.

“Then we had more exposed soil and less water infiltration because the roots weren’t as deep,” he said. “The annual crops and drainage tile started to create this leaky system.”

This “leaky system” refers to what is not absorbed by the crops on the field, most dangerously, in this case, fertilizer.

“It’s a leaky system because it’s not in sync,” said Iowa water quality expert Chris Jones, author of The Swine Republic book (and blog).  “And farmers know they’re going to lose some fertilizer. As a consequence, they apply extra as insurance.”

Fertilizer as Poison

The U.S. is the top corn-producing country in the world, with states like Iowa, Illinois, Nebraska, and Minnesota supplying 32 percent of corn globally. Corn produces lower yields if it is nitrogen deficient, so farmers apply nitrogen-heavy fertilizer to the crop. In fact, they must use fertilizer in order to qualify for crop insurance. The ammonia in the fertilizer oxidizes existing nitrogen in the soil, turning it into highly water-soluble nitrates that aren’t fully absorbed by the corn. Those nitrates leak into aquifers.

In 1960, farmers used approximately 3 million tons of nitrogen fertilizer a year. In 2021, that number was closer to 19 million. Farmers can use a nitrogen calculator to determine how much nitrogen they need—but nearly 70 percent of farmers use more than the recommended amount.

“Other people also have an American dream, and they want to be able to turn on their faucet and have clean water, or know that if they put their baby in a bath, they’re not going to end up in the hospital with major organs shutting down because they have been poisoned.”

As Jones explains in his blog, even with “insurance” fertilizer use, yields can often turn out the same: “What happened to that extra 56 pounds of nitrogen that you bought? Well, some might’ve ended up sequestered in the soil, but a lot of it ran off into lakes and streams or leached down into the aquifer (hmm, do you reckon that’s why the neighbor’s well is contaminated?), and some off-gassed to the atmosphere as nitrous oxide, a substance that has 300 times more warming potential than carbon dioxide.”

Commercial fertilizer is just one contributor to high nitrate levels in groundwater. The other main factor, manure, is also increasing as CAFOs become more prevalent.

Nancy Utesch and her husband, Lynn, live on 150 acres of land in Kewaunee County, Wisconsin, where they rotationally graze beef cattle. In 2004, a family nearby became very ill from E. coli poisoning in their water.

“I was really upset that this had happened in our county,” she said. “A lot of the support was for the polluting farmer, and you know, farming is right there with the American flag and grandma’s apple pie.”

Utesch worries that the current system of industrialized agriculture has created a world where people living closest to the polluters do not have access to clean water themselves, and are afraid to speak out against the actions of their neighbors.

“Other people also have an American dream, and they want to be able to turn on their faucet and have clean water, or know that if they put their baby in a bath, that they’re not going to end up in the hospital with major organs shutting down because they have been poisoned,” she said. “If they clean a scrape because their grandchild fell down in the driveway, they could be hurting them if they use the water from the tap.”

The Plight of the Small Town

In June 2022, fertilizer runoff pushed Des Moines Water Works, the municipal agency charged with overseeing drinking water, to restart operations of their nitrate removal system—one of the largest in the world—at a cost of up to $16,000 per day. Des Moines finances its removal system from its roughly 600,000 ratepayers.

“Financially, Des Moines can spread out needed treatment over many thousands of customers, whereas a small town can’t do that,” Jones said. “If you have a small town of 1,000 people, your well gets contaminated, and you need a $2 million treatment plan to clean up the water, that’s a burden.”

“Financially, Des Moines can spread out needed treatment over many thousands of customers, whereas a small town can’t do that.”

While cities like Des Moines are willing to pay the cost to remove nitrates, other small communities will have a tougher time doing so. And once their aquifer is contaminated, “it doesn’t go away for a long time, in some cases, thousands of years,” Jones said.

We’ll bring the news to you.

Get the weekly Civil Eats newsletter, delivered to your inbox.

Utica, Minnesota, which has fewer than 300 residents, has two deep wells, both measuring at unsafe levels for nitrates.

“[Residents are] scared to death,” Broberg, who lives in a neighboring town, said. “The city has investigated water treatment expenses at around $3 million for reverse osmosis, and they only last 10 years. A town of 85 households can’t amortize that debt by themselves.”

The town has applied for a grant from the state and is waiting to hear back.

Another nearby town, Lewiston, dug a new, deeper well to solve their nitrate problem.

“They went down there, and the water was contaminated with radium. It’s radioactive,” Broberg said. “So they kept their nitrate-contaminated well and their radium-contaminated well and blended the water so that it doesn’t exceed the health risk limit for either nitrates or radium.”

However, as Chris Rogers reported in the Winona Post, that plan didn’t quite work. Thus, Lewiston dug another well at a cost of $904,580, and is now sourcing all of their water from that new well. That well is now testing trace amounts of nitrates and has less radium than before.

Many rural residents also rely on private, personal well systems, which aren’t regulated for contaminants, to source their water. Forty million people rely on well water nationwide.

“Public water systems have these maximum contaminant levels that are set by the EPA. There are rules and regulations that they have to follow, but private wells aren’t covered by the Safe Drinking Water Act,” said Stacy Woods, research director of the food and environment program at the Union of Concerned Scientists. “It’s really on individual well owners to decide whether to test their wells and what contaminants to test their wells for, and these tests can be really expensive.”

Broberg and his group are working to extend the protection of the Safe Drinking Water Act to well water. In southeast Minnesota, the EPA agreed to the plan, though the path forward is still uncertain as funding packages move through the legislature.

“I’ve spoken with people who simply don’t want to test their well water because they can’t afford to do much about it if they find out that their nitrate levels are unsafe.”

Without these protections in place, or intervention at the pollution source, rural residents often find the responsibility of clean water falling on them.

“I’ve spoken with people who simply don’t want to test their well water because they can’t afford to do much about it if they find out that their nitrate levels are unsafe,” Food and Water Watch Legal Director Tarah Heinzen said. “They are basically powerless to protect their drinking water resources from sources of pollution that aren’t being adequately regulated by the state.”

The solution, according to Woods, “is to protect the drinking water sources from that pollution in the first place.”

Conservation on the Farm

One way to do this is by using less fertilizer on the field. Another is to introduce on-the-field and edge-of-field conservation practices, like Tesdell is doing on his Iowa family farm.

Tesdell’s farm is not the typical Iowa farm, which averages 359 acres. Tesdell’s is 80. He does, however, rent 50 acres to a neighbor who grows corn and soybeans, like most Iowa farmers.

Where Tesdell’s farm differs is how he deals with excess nitrate. In 2012, Tesdell, who has always been drawn to conservation, became interested in adding cover cropping to his fields. Through his research, he came across other conservation practices such as wood chip bioreactors. He installed his first bioreactor that same year.

“There’s a chemical and biological reaction between the wood chips and the nitrate in the tile water,” Tesdell said. “Much of the nitrate then is turned into nitrogen gas, which is a harmless gas. We don’t take out 100 percent of the nitrate, but we take out a good percentage.”

According to Iowa State University, a typical bioreactor costs around $10,000 to design and install. Tesdell paid for his bioreactor partly out of pocket, but also acquired funding from the Iowa Soybean Association. For his saturated buffer, an edge-of-field practice that redirects excess nitrates through vegetation, Tesdell received funding from the USDA’s Environmental Quality Incentives Program (EQIP). To install the saturated buffer, Tesdell needed his neighbor to agree.

Thank you for being a loyal reader.

We rely on you. Become a member today to read unlimited stories.

“We put that one on a tile that actually comes from my neighbor’s farm. Because the creek is going through my farm, it’s a more direct route to come off a hill [on] his farm,” he said. “Neighbors need to work together.”

Roughly 80 percent of the farmland in Iowa is owned by offsite landlords, who rent it out to farmers. Tesdell cites this as  a roadblock to conservation practices.

“If the landowner doesn’t care, why would an operator care? They want to pull in with their 24-row planter, plant their corn, come in with the 12-row corn head in October and harvest, then truck it off to the ethanol plant,” he said. “I don’t blame them.”

Iowa currently has a “Nutrient Reduction Strategy” plan, which outlines voluntary efforts farmers can take to reduce their pollution. There is no active legislation that limits how much fertilizer farmers use on their cropland.

Heinzen, of Food and Water Watch, explained that agricultural pollution is largely unregulated, with the exception of concentrated animals feeding operations (CAFOs).  “In fact, even most CAFOs are completely unregulated, because EPA has completely failed to implement Congress’s intent to regulate this industry, which we’re suing them over,” she said, referring to a new brief filed by multiple advocacy groups in February aimed at upgrading CAFO pollution regulation.

Even Des Moines Waterworks, with its state-of-the-art nitrate removal facility, is calling for change.

“We cannot keep treating water quality only at the receiving end,” spokesperson Melissa Walker said. “There needs to be a plan for every acre of farmland in Iowa and how its nutrients will be managed, as well as every animal and its manure.”

“You’re either going to have to change your practices, change your farming, or you’re going to have the accept the risk of preventable disease.”

Some communities have sued for damages related to nitrate-contaminated groundwater. In Millsboro, Delaware, residents received a payout but still have contaminated water. In Boardman, Oregon, five residents are suing the Port of Morrow and multiple farms and CAFOs due to their well-water testing “at more than four times the safe limit established by the U.S. EPA,” Alex Baumhardt reported in the Oregon Capital Chronicle.

A few weeks ago, 1,500 tons of liquid nitrogen were spilled into an Iowa river. No living fish were found nearby. Today, polluted water flows downstream into the Gulf of Mexico, where it causes “dead zones” stripped of marine life.

“You’re either going to have to change your practices, change your farming, or you’re going to have the accept the risk of preventable disease,” Broberg said. “And you need to put that equation in your family budget. If you’re going to get bladder cancer, diabetes, birth defects, juvenile cancers—what are those going to cost?”

When asked why protecting water is so important, Tesdell paused and looked away. His voice cracked with emotion. “It’s for the grandkids.”

Nina Elkadi is a writer from Iowa who reports on the intersection of climate change and agriculture. Her work also explores the manipulation of science and how corporate negligence affects consumers and workers. Read more >

Like the story?
Join the conversation.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  1. Dan Lefever
    There is no need to use nitrate fertilizers. There is 28 tons of nitrogen above every acre of land and water. All that is needed, is to restore soil biology, and all the nitrogen needed by the plant can be produced by the microbiology. Do wild areas need to have nitrogen fertilizers applied to them to grow? No, they get all they need via the soil microbiology. The same can be done for any crop plants in a few years time, by rebuilding soil health. There should be a heavy tax on all nitrate and anhydrous ammonia that is purchased, and utilize it to fund the cleanup of drinking water. Meanwhile the use of nitrate fertilizers should be curtailed and eventually eliminated; and only natural ammonium and protein based nitrogen fertilizers should be allowed, during transition. Even if all nitrate fertilizer use was curtaileded immediately, it may take a thousand years for nitrate contaminated groundwater to be remediated, if it is ever possible at all!

More from



hickens gather around a feeder at a farm on August 9, 2014 in Osage, Iowa. Photo by Scott Olson/Getty Images

What Happened to Antibiotic-Free Chicken?

With the biggest poultry company in the country backtracking and other commitments to raising healthier birds unmet, the future is rockier than it once seemed.


Nik Sharma Offers His Top Tips for Home Cooks to Fight Recipe Fatigue

Nik Sharma baking at left, and tossing a chickpea dish at right. (Photo credit: Nik Sharma)

Far From Home, the Curry Leaf Tree Thrives

Zee Lilani of Kula Nursery stands among her curry leaf tree starts in Oakland, California. (Photo credit: Melati Citrawireja)

A Guide to Climate-Conscious Grocery Shopping

Changing How We Farm Might Protect Wild Mammals—and Fight Climate Change

A red fox in a Connecticut farm field. (Photo credit: Robert Winkler, Getty Images)