Minnesota sues 3M again over PFAS contamination near Cottage Grove

Minnesota has sued 3M again, saying PFAS from the company’s Cottage Grove plant are still contaminating groundwater and the Mississippi River and creating what the Minnesota Pollution Control Agency called an “ongoing and continuous harm” to the state.

The lawsuit was filed May 1 in Washington County District Court and says testing near the site found PFOS at one sampling location at 310,000 parts per trillion, far above Minnesota’s site-specific standard of 0.05 parts per trillion. The MPCA says the pollution violates state permits and regulations, and it is asking for civil penalties of up to $30,000 per violation per day, along with cleanup costs, injunctive relief and compensation for damage to wildlife and natural resources.

The agency also says 3M has fallen behind on cleanup work required under a 2022 administrative order and that the company’s groundwater extraction network is not doing enough to stop the spread. The area near the Cottage Grove facility is already under a fish consumption advisory from the Minnesota Department of Health, another sign that the contamination has moved beyond an abstract legal dispute and into the daily question of what people can safely eat and drink.

3M has moved to transfer the case to federal court, arguing that some of the contamination stems from work the company performed as a contractor for the U.S. military, including firefighting foam made to Department of Defense specifications. The company has said it has invested heavily in cleanup and disputes liability tied to that military-directed production.

The new filing lands against a long history of PFAS litigation in Minnesota. The state sued 3M in 2010 over contamination in the east Twin Cities metro area, and that case ended in a Feb. 20, 2018 settlement worth $850 million. After expenses, about $720 million was set aside for drinking-water and natural-resource projects in the east metro region. A separate federal settlement finalized in 2024 requires 3M to pay $10.3 billion over 13 years to help remediate PFAS in drinking water systems nationwide.

PFAS are human-made chemicals known for their persistence in water, soil, fish, wildlife and people, which is why they are often called forever chemicals. Some exposures have been linked to liver and thyroid disease, fertility problems and low birth weight. 3M says it completed its planned exit from PFAS manufacturing at the end of 2025.

For Otter Tail County residents, the lawsuit does not name a local contamination site, but it does matter. The case shows Minnesota is still pushing for tougher cleanup, sharper water testing and bigger liability claims after years of PFAS releases. That effort affects public trust in drinking water systems across the state, including communities in Perham and throughout Otter Tail County, where residents depend on regulators to catch long-lived contaminants before they become another expensive cleanup.