Southeast Minnesota Runoff Pollutes Beyond Local Area

WINONA COUNTY – Jeff Broberg’s well sits inside a wooden shed not too far from a field he rented about a decade ago to a local farmer.

One day, Broberg discovered the farmer was fertilizing with hog manure. In doing so, combined with the commercial fertilizer he was already using, the farmer was almost doubling the amount of nitrogen on the field in hopes of producing a better corn yield.

Not all of that nitrogen went to the corn. Some of it seeped into the groundwater and was pumped through the well that supplied the water Broberg drank in the form of nitrate, which is made when nitrogen and oxygen combine.

It’s an alarming local impact of a persistent problem that washes far downstream through the Mississippi River watershed, eventually ending up in the Gulf of Mexico, where nitrates are one cause of a low-oxygen “dead zone” that chokes off plant and aquatic life

In southeast Minnesota, Broberg’s well water tested at 22 parts per million nitrate – more than double what the U.S. Environmental Protection Agency says is the safe limit for the contaminant.

Broberg, a retired geologist who’s now a clean water advocate, had his well tested when he first bought the house in 1986. For the first decade he lived there, it hovered close to 10 parts per million nitrate, the EPA’s limit. When it started to test above that, he began to haul water from a friend’s house in a nearby town.

Finally, he installed a system that reduced nitrate levels in the water he drank, a system that protected him after the incident with the farmer.

But he has questions about what he might have been exposed to when he was drinking the water straight out of the tap years before.

In 2023, he was diagnosed with chronic kidney disease. Drinking water with elevated nitrate has been linked in some research to kidney dysfunction. Though it’s nearly impossible to determine the exact cause of such ailments because other lifestyle factors can play a part, he can’t help but wonder what role the water played.

Downriver to the Gulf of Mexico

Broberg’s home in rural Winona County is about a dozen miles as the crow flies from the Mississippi River. The nitrate polluting his well water links him directly to the other end of the river, and the dead zone that blooms there every summer.

This year officials have forecast that this dead-zone area will be about 5,827 square miles – larger than average, roughly the size of Connecticut and more than twice the target size that a task force of scientists and government officials aims to see by 2035.

Progress on decreasing it has been slow-going, despite billions of dollars in investment.

Still, a 2023 public opinion survey conducted by the University of Missouri, in partnership with the Mississippi River Basin Ag & Water Desk, showed only about 25% of Mississippi basin residents understood the causes of the dead zone.

But upstream communities are starting to recognize there are costs closer to home.

Broberg and hydrologist Paul Wotzka are both board members of the Minnesota Well Owners Organization, which in April 2023 was among several groups to ask the EPA to intervene in their region’s nitrate contamination problem. In the fall of 2023 the EPA responded saying that “further actions” were needed to protect human health and directed Minnesota state agencies to develop a plan to test drinking water and give residents alternative water sources as soon as possible.

Anything that cuts nutrient pollution upstream will eventually help the Gulf, Wotzka said. And issues like these are personal enough to make people sit up and pay attention.

“That’s why we focus on the kitchen tap. Everybody’s got one, everybody should be concerned,” Wotzka said. “You’ve got to get people to focus on improving the water resource that is closest to them.”

Hydrologist Paul Wotzka picks up sand from a rock face near his home along the Mississippi River near Weaver that shows the region’s karst geology – porous rock through which water, along with fertilizer or manure applied on the ground above, can easily travel, leading to well water contamination. (Photo by Mark Hoffman, Milwaukee Journal Sentinel)

Polluted water becomes a public health problem

The spotlight was on southeast Minnesota when residents approached the EPA for help with their nitrate-contaminated wells. But it’s a much more widespread – and costly – problem.

Other Midwest states with economies driven by agriculture, such as Wisconsin, Iowa and Nebraska, have pockets of nitrate pollution where soils are sensitive and porous, allowing the contaminant to easily seep into groundwater. Iowa environmental groups filed a similar petition to the EPA in April of 2024.

Private well owners are particularly vulnerable because they are responsible for testing and treating their own water. But it can be burdensome for public water utilities, too.

The small southeast Minnesota town of Utica (located along the northern edge of the Root River watershed) is spending $2 million to drill a deeper well in hopes of keeping contamination out. On a larger scale, the Des Moines (Iowa) Water Works has spent millions of dollars on a nitrate removal facility to keep nitrates from nearby rivers out of the city’s water supply – a cost that’s ultimately passed on to ratepayers.

Then there’s the cost to human health. The most well-known health problem linked to consuming nitrate in water is blue baby syndrome, which occurs when a lack of oxygen in the blood turns infants’ skin blue. The link was first reported in 1945, and hundreds of cases were reported in babies drinking formula prepared with well water.

A few decades later, the EPA set the maximum contaminant level for nitrate at 10 mg/L – lower than what made the babies sick – and thanks to the public health campaign that communicated that limit, the condition is now relatively rare.

But there’s growing attention to the health impacts that consuming water high in nitrate can have on older children and adults, including colorectal cancer, thyroid disease and birth defects. A 2018 review of studies of such impacts found that risk of some of those illnesses increased even when the nitrate in people’s drinking water was below the maximum contaminant level.

In Nebraska, where the pediatric cancer rate is among the highest in the nation, University of Nebraska Medical Center research found that areas of the state with higher rates of pediatric cancer also have higher nitrate levels.

Researchers urge that more studies are needed to firmly draw a line between drinking water nitrate and these conditions. Broberg and Wotzka said they limit their discussions about health impacts when speaking with others because they’re not doctors. But in areas – like southeast Minnesota – with high nitrate levels, people do wonder if there’s a connection.

The health issues associated with nitrate are common in his community, Broberg said. His neighbors ask, “Aren’t there clusters of this going on?”

Going to the EPA turned up the volume on Minnesota’s nitrate issue, said Carly Griffith, water program director for the Minnesota Center for Environmental Advocacy, the group that filed Minnesota’s petition to the EPA.

“My hope is that it’s not always necessary to reach a crisis level to see this kind of coordinated action,” Griffith said.

Algae covers a large portion of Round Lake, a spring-fed lake along the Mississippi River near Trempealeau, Wisconsin. (Photo by: Mike De Sisti, Milwaukee Journal Sentinel)

Excess nutrients cause toxic blooms

It’s not just drinking water that’s in jeopardy. Surface water filled with too much nitrogen and phosphorus from fertilizers can kill fish – a common problem in southeast Minnesota streams – and create conditions ripe for toxic algae blooms.

These blooms, which typically occur in warm, nutrient-rich water, contain toxins that can sicken people and animals that come into contact with them. In 2021, federal health officials reported 117 human illnesses and more than 2,700 animal illnesses linked to the blooms.

Even people who don’t get sick may find themselves affected. Toxic blooms, as well as bacteria like E. coli that can get into the water by way of manure or sewage, close beaches across the country each year.

It’s an annoyance for would-be swimmers, but also a detriment to local tourism economies.

In Madison, Wisconsin, the state’s capital city and its flagship university sit on a chain of five lakes surrounded by farmland. The lakes have historically struggled with excess phosphorus from farms, yielding an unpleasant, soupy green sight some summer days.

“If it’s a gorgeous day, there’s nothing else like it in the entire world,” James Tye, founder and executive director of the Clean Lakes Alliance, said of visiting the university’s lakeside terrace.

But on days when algae blooms proliferate, he said, conditions can be downright dangerous if those blooms are releasing toxins into the water that people are recreating in.

Tye said once water exits the Madison lakes, it takes only 40 days to travel the length of the Mississippi River and end up in the Gulf.

But his organization doesn’t spend a ton of time talking about that. He knows people can only pay attention to so much.

“Phosphorus is the thing that the community has decided we can make the quickest and biggest change to,” he said.

Efforts to clean up the lakes have been moderately successful, but they now face new climate threats. A shorter winter season means there’s more time for algae blooms to form, and more severe rains make it easier for excess phosphorus to wash downstream.

The Mississippi River basin drains water from more than 40 percent of the country into the Gulf of Mexico. Map data: U.S. Geological Survey, World Bank. (Image by Annie Ropeik, Ag & Water Desk)

Local issues could be the key to upstream solutions

There have been some efforts over the years to directly connect people at the upper end of the Mississippi River with people near the Gulf.

Wotzka participated in a conference that hosted prominent Gulf of Mexico dead zone researcher Nancy Rabalais in the mid-1990s. She spoke to Minnesotans about how the nutrient pollution coming from Midwest farms was destroying coastal shrimpers’ and fishers’ livelihoods.

Still, “to draw that connection to the Gulf is just extremely hard to do,” Wotzka said. “But when you’re talking about contaminated drinking water, it’s a different story.”

Joe Ailts, an agronomist in northwest Wisconsin, understands that all too well. His own water has to be treated for high nitrate, something that’s on his mind while he works with farmers who are adopting practices that will slow runoff.

For people who are generally concerned about water quality, the Gulf’s dead zone might be a motivator, Ailts said.

But for others, it’s the hyperlocal issues that will resonate.

“The mindset that’ll take someone from no action to action is seeing it personally,” he said.