Minnesota Agriculture Department Declines to Strengthen Fertilizer Rule Despite Ongoing Nitrate Contamination in Drinking and Surface Water
DATE: 09/01/2026 CONTACT: Mair Allen, MCEA, mallen@mncenter.org, 414-828-8815
St. Paul, Minn – The Minnesota Department of Agriculture (MDA) announced Monday that its rule governing commercial fertilizer – called the groundwater protection rule – does not need to change despite clear evidence that runoff from excessive commercial fertilizer application is causing nitrate contamination in drinking water in at least two areas of the state.
A Ramsey County District Court judge ordered the agency to review the rule last September after the Minnesota Center for Environmental Advocacy (MCEA), the Minnesota Well Owners Organization and Minnesota Trout Unlimited filed a lawsuit against MDA and the Minnesota Pollution Control Agency for their failure to curb the state’s longstanding nitrate pollution problem. The suit identified the state’s ineffective groundwater protection rule and feedlot rule as central to the issue.
“The Groundwater Protection Rule is seven years old, and thousands of Minnesotans in the state’s karst and Central Sands regions still have drinking water that is dangerously contaminated with nitrate,” said Joy Anderson, Legal Director for the Minnesota Center for Environmental Advocacy (MCEA). “I don’t know what could be more telling that the rule isn’t working than that.”
“We’ve heard the argument that Minnesota just needs to wait longer for the rule to work, but the fact is, the Groundwater Protection Rule will never clean up Minnesota’s water because it doesn’t force producers to make meaningful changes,” Anderson continued. “With this court order, the agency had a chance to use science-based solutions to impose common-sense regulations that will protect public health, the environment, and our climate. Instead, they chose business as usual."
Minnesota’s groundwater protection and feedlot rules regulate the agricultural sector’s commercial fertilizer and manure application, the two biggest sources of nitrate pollution in the state. The groundwater rule, which applies to commercial fertilizer, is under MDA's jurisdiction; the feedlot rule, which applies to manure, is under MPCA's jurisdiction. MPCA already concluded that the state’s feedlot rules need revision.
When nutrients from manure and commercial fertilizer are applied to agricultural fields in excess of crop needs, they wash away and seep into groundwater, potentially contaminating drinking water sources with unsafe nitrate levels. Minnesota’s nitrate pollution problem is the most severe in the state’s karst and Central Sands regions, which are heavily agricultural and have geology that makes them particularly vulnerable to groundwater pollution. Drinking water testing data from the karst and Central Sands regions consistently show nitrate levels above federal limits.
Exposure to nitrate levels above the current 10 mg/L health limit can cause Blue Baby syndrome in infants and other vulnerable populations. Recent research, however, shows that long-term exposure at rates lower than the health limit can also have devastating impacts. Nitrate levels as low as 3 mg/L have been linked to birth defects as well as cancers. The Environmental Protection Agency (EPA) had been considering lowering the federal health limit amid new research on health impacts, but the Trump administration dropped the effort.
Nearly 400,000 Minnesotans live in the karst region alone, and 94,000 rely on private wells, which are at higher risk of nitrate contamination due to a lack of public oversight. The EPA found that at least 9,200 residents with private wells in southeastern Minnesota are at risk of drinking water contaminated above the federal health limit for nitrate. Even more residents are likely at risk from drinking water at unsafe levels below the federal limit.
The urgency of the issue is underscored by a recently updated study by University of Minnesota associate professor Bonnie Keeler on the human health impacts linked to consuming nitrate-contaminated drinking water. The study estimates that nitrate-attributable health conditions in Minnesota cost $745 million annually, including direct care costs and quality-of-life impacts. The estimate is only for people who get their water through municipal public water suppliers and does not include costs to private well users.
In addition to harming human health, nitrate pollution contributes to toxic algal blooms that harm fish and other aquatic life and are rendering an increasing number of lakes, rivers, and streams in Minnesota unswimmable and unfishable.
Groundwater supplies substantial water flow to many of Minnesota’s streams. When the groundwater is contaminated, pollutants like nitrates are transported into connected streams, degrading surface-water quality.
“We’re disappointed MDA failed to acknowledge that its groundwater protection rule is not adequate to protect aquatic life and Minnesota’s public waters,” said Minnesota Trout Unlimited Executive Director John Lenczewski. “The state’s own water quality data shows that 75% of streams tested in southern Minnesota routinely exceed nitrate levels harmful to aquatic life, including trout and aquatic insects.”
The EPA mandated state action on Minnesota’s nitrate pollution crisis after MCEA led a coalition of environmental groups to petition the federal government to intervene in April 2023 on behalf of endangered residents. The agency ordered the state to immediately provide clean drinking water alternatives to affected residents and make a plan to address the root causes of the pollution.
The plaintiffs involved in this case are reviewing the agency’s determination and considering next steps.
Questions and/or interview requests about this press release can be directed to Mair Allen.
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