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Even in retirement from a hydrology career, Paul Wotzka keeps tabs on soil layers in southeastern Minnesota’s bluff country.

“We have a groundwater sensitive parameter down here,” Wotzka, a prior state regulator, said about southeast Minnesota’s Driftless region known for its sweeping limestone bluffs, swiss-cheese like karst and cool water trout streams. 

Not far away but in the same region, Jennifer Biederman watches on behalf of trout anglers for the way chemical runoff can elevate nitrate levels in sensitive fishing streams.

“We do know that nitrates, over time, create ecological disturbances and degradation of cold water streams,” Biederman said. 

Their methods and reasons might vary, but Wotzka and Biederman are joined in a legal fight lodged by environmental and conservation groups against two state agencies. Their aim is to speed up meaningful regulation to mitigate high nitrate concentration in southeastern Minnesota, arguing it has a detrimental effect on human and ecological health. 

In January, a coalition of groups filed a lawsuit in Ramsey County District Court against the Minnesota Pollution Control Agency and the Minnesota Department of Agriculture. It wasn’t for monetary damages. It attempts to compel the state agencies to enact stricter rules on manure and commercial fertilizer application. 

For their part, the agencies acknowledge the longstanding problem with elevated nitrate levels in groundwater and surface waters in certain regions, some of it caused by human sources. But in court filings they deny it constitutes pollution that is “necessarily dangerous.”

“Nitrate is not just a Minnesota issue, it is a national concern and MPCA is leading the country in its efforts to reduce nitrate levels,” an attorney for the agency wrote in a March filing.

The next hearing in the case is set for Aug. 26 before a Ramsey County judge. Should the case go to trial, that would take place next April under the most-recent schedule.

Pesticides and fertilizers for commercial agriculture can move quickly into the groundwater.  Some 90,000 Minnesotans who live in this region rely on private wells for drinking water. 

Consuming water with high nitrate levels poses a health risk to humans. 

“We have really good data from the state agencies themselves that says the drinking water here, in a lot of cases, violates what the federal government has said is safe for people to drink,” said attorney Joy Anderson with the Minnesota Center for Environmental Advocacy. “We need to get that cleaned up. The state agencies have not passed regulations that, in our view, are sufficient to do that.”

Nitrates can occur naturally but is also a byproduct of nitrogen fertilizer that farmers in the Midwest use lots of to grow corn and soybeans. 

published this month shows that prenatal exposure to nitrates in drinking water could increase the risk for low birth weight and pre-term birth. 

“Exposure to nitrate above the EPA threshold increases the risk of very low birth weight, which is a very, very risky outcome for children,” said study author Jason Semprini. 

Semprini is an assistant professor at Des Moines University in Iowa, where there are some of the highest concentrations of nitrates in rivers. That prompted the water utility in Des Moines to prohibit lawn watering. 

Semprini looked at more than 357,000 births and water records from the 1970s and 1980s. He says small levels of nitrate exposure are associated with increased risks of preterm birth and low birth weight. 

“Nitrate in groundwater has been increasing,” Semprini said. “So there’s more people exposed to nitrate in their water.”

Exposure even under the EPA’s standard of 10 milligrams per liter can result in health risks.

Ground and surface water interact more quickly in the Driftless region of southeast Minnesota, northeast Iowa, southwestern Wisconsin and northwest Illinois. 

Wotzka, the retired hydrologist, is now with the Minnesota Well Owners Organization. He likes to show visitors to his farm near Weaver a road cut through a high bluff. There are layers of porous sandstone and limestone and at the top a layer of topsoil. 

“That’s where everything grows,” Wotzka said, pointing out the thin layer topsoil at the top of the bluff. “You’re living in a groundwater sensitive area.”

Wotzka’s organization is one of the plaintiffs in the lawsuit. Minnesota Trout Unlimited and the Minnesota Center for Environmental Advocacy are the others.

The lawsuit asks the MPCA, which oversees feedlots, to pass stricter rules to govern application of manure. It also asks the Department of Agriculture, which has authority over commercial fertilizer, to pass stricter rules about the way it is used. 

The agencies would not discuss the pending litigation with MPR News but issued a joint statement. It says the state is committed to a “robust, inclusive and transparent process” and believes “the permit and rulemaking are legally sound.”

Minnesota farm groups also see the lawsuit as unneeded.

“Minnesota has a transparent processes for rulemaking and review by state agencies, and this lawsuit could set a precedent that undermines the process,” Minnesota Corn Growers Association president Jim Kanten 

But conservation advocates are also concerned. Minnesota Trout Unlimited is also part of the lawsuit. There is growing concern that the cool water streams of the driftless region are being choked out by nitrate contamination. 

This part of Minnesota is a magnet for anglers who fly fish. 

“These trout in these streams are very opportunistic,” said Biederman, Minnesota Trout Unlimited’s habitat director. “They will go after just about anything.”

Biederman said high levels of nitrate can reduce the survival of trout in this region. 

“With relatively thin layers of soil and sediment, which normally acts like a filter for things like nitrates that you want to be able to naturally filter, filter out before they reach the groundwater. Here we don’t have that filtration system, and because of the porous nature of the geology, those nitrates actually get into our groundwater quickly,” Biderman said. 

The plaintiffs hope either through a court decision or settlement the agencies will be forced to open up a process to the public so Minnesotans can weigh in on the rules that affect public health in the region. 

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Clay Masters

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Environmental groups and concerned well owners in southeast Minnesota hope a lawsuit against the Minnesota Pollution Control Agency and the Department of Agriculture will open up the rulemaking process for manure and commercial fertilizer.

Environmental and concerned well-owners in southeast Minnesota hope a lawsuit against the Minnesota Pollution Control and Department of Agriculture will open up the rulemaking process for manure and commercial fertilizer.

Environmental, conservation groups apply pressure on nitrate contamination in southeast Minnesota

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