Minnesota sues 3M again over PFAS contamination in Cottage Grove

Minnesota has sued 3M again, accusing the company of letting PFAS from its Cottage Grove plant keep moving into groundwater and the Mississippi River even as cleanup work ordered in 2022 remains behind schedule. The Minnesota Pollution Control Agency filed the case May 1 in Washington County District Court and is seeking civil penalties, cleanup costs, injunctive relief and compensation for damage to natural resources.

The filing underscores why PFAS remains a drinking-water issue, not just a courtroom fight. State records say testing near the Cottage Grove site found PFOS at levels as high as 310,000 parts per trillion at one location, compared with Minnesota’s site-specific standard of 0.05 parts per trillion. The area near the plant was already under a fish consumption advisory, a reminder that contamination can move from groundwater into rivers and into the food chain.

For the east metro, the health stakes are concrete. The MPCA says PFAS contamination there covers more than 150 square miles and affects drinking-water supplies for more than 140,000 Minnesotans. That is where the state has spent decades tracking the chemicals, and where long-term exposure concerns are most immediate.

The current lawsuit also fits into a long paper trail. 3M notified the MPCA in 2002 that PFAS had been detected in a production well at its Cottage Grove facility. By 2004, PFAS contamination had been found in drinking-water supplies in parts of the eastern metropolitan area. In 2007, the MPCA and 3M negotiated a consent order to move investigation and cleanup of three disposal sites through the Superfund process. Minnesota then sued 3M in 2010 over alleged damage to drinking water and natural resources in the east Twin Cities metro, and that case settled on Feb. 20, 2018, for $850 million. After expenses, about $720 million was set aside for drinking-water and natural-resource projects in the east metro.

3M is pushing back. The company wants the case heard in federal court and argues that some of the contamination came from firefighting foam it made for the U.S. military under Department of Defense specifications. It says it warned the federal government about PFAS risks and points to its broader cleanup spending and its planned exit from PFAS manufacturing, which it said it completed at the end of 2025.

For Beltrami County, this lawsuit does not change local drinking-water rules or fish advisories on its own. Its real significance is broader: PFAS contamination can persist for years, spread through water systems and trigger state monitoring, health advisories and cleanup obligations long after the original manufacturing stops. Minnesota’s newest case shows that the cost of that contamination is still being fought over in court.