The MPCA will solicit comments for an updated draft wastewater permit for the 3M Chemical Operations manufacturing facility in Cottage Grove. This draft permit, one of the most rigorous in state history, adds new water quality protections for the Mississippi River and mandates the removal of certain per- and polyfluoroalkyl substances (PFAS) to levels below detection.
Our role
The MPCA is committed to ensuring that every Minnesotan has healthy air, sustainable lands, and clean water — including the Mississippi River.
By issuing wastewater permits, the MPCA protects water quality for aquatic life, recreation, and human fish consumption by limiting pollutant discharge as required by federal regulations and applicable water quality standards
Public comments are an important part of the permitting process and will shape the final permit. The MPCA is grateful to everyone who provided comments during the first 60-day public comment period, which ended on Aug. 30, 2024. The MPCA has carefully reviewed every comment and updated the draft permit based on this feedback and the state rules and statutes that govern the permitting process.
This updated draft permit began public notice on Dec. 18 for a 45-day public comment period, ending Feb. 3, 2025. The MPCA will review additional comments received during this time before issuing a final permit. Issuing a final permit is important to begin the environmental protections it mandates. Updates will be shared through our GovDelivery email list for the 3M Cottage Grove permit.
Please note: For comments submitted during the initial public comment period, no resubmittal is required. They have already been accepted.
Review and comment on the permit
The comment period for the wastewater permit for 3M's facility in Cottage Grove is open through Feb. 3, 2025.
Project information
3M applied for a reissued permit for the facility, which produces a wide range of products including abrasives, chemicals, polymers, resins, and tapes. The facility also manufactures various PFAS. It treats its own wastewater, stormwater, and cooling water as well as contaminated groundwater and leachate from a nearby landfill. Additionally, the facility handles water from a local power station and from decommissioning activities related to its incinerator.
The facility makes use of an advanced PFAS wastewater treatment system that will treat all types of PFAS, not just those types with limits established in the permit, along with many other pollutants from wastewater, stormwater, and groundwater sources.
Under the draft water quality permit, the facility would be allowed to discharge up to 15.2 million gallons of treated wastewater per day to an unnamed creek that flows into the Mississippi River.
The revised draft permit remains highly protective of health and the environment. It calls for increased monitoring of groundwater, the Mississippi River, and aquatic life to ensure compliance and public transparency. It also requires 3M to file public reports and to hold an annual community meeting. The MPCA will publish water quality monitoring data from the facility online monthly.
The permit sets stringent limits on the levels of pollutants, including PFAS, in the facility's wastewater. Some PFAS limits are so low they are undetectable. The MPCA must set limits based on federal law, state rules, and water quality standards or criteria.
After the initial public comment period, the MPCA made about 30 changes within the 415-page draft that keep the permit strong and within applicable rules. These changes include corrections, technical adjustments, additional monitoring, and new reporting requirements. Public feedback on the revised draft permit is welcomed until Feb. 3, 2025.
All changes can be found in a redlined version of the revised permit.
Examples of changes include:
- The revised permit corrects a math error in how PFAS pollution limits were calculated. The correction increases limits by a fraction of one part per trillion. In practical terms, PFAS pollution compliance limits in the revised draft remain unchanged. Limits that were below detection capability remain so.
- Limits were removed on one type of PFAS known as PFHxA because there is no reasonable potential for it to be detected at all. Reasonable potential is the likelihood or capacity of an activity, entity, or condition to produce a specific outcome or effect that is significant enough to warrant oversight or action. Minnesota rulemaking requires MPCA to not require limits when no reasonable potential detection exists.
- The permit requires 3M to monitor for PFHxA and over 60 other types of PFAS. The advanced PFAS wastewater treatment system that 3M will use will be effective with all types of PFAS and other pollutants — not just those with limits.
- Monitoring data will be public.
- The revised permit adds a limit based on how aquatic life respond to treated water, called an acute whole effluent toxicity limit. The revised permit also adds requirements to monitor treated water for total aluminum, boron, arsenic, and cobalt.
Key dates
- July 1, 2024: First draft permit is released and a 60-day public comment period begins
- July 29, 2024: First virtual public information session (recorded)
- July 31, 2024: In-person community meeting in Cottage Grove.
- Aug. 20, 2024: Second virtual public information session.
- Aug. 30, 2024: Deadline for public comments on the draft permit, the permit fact sheet, and site-specific water quality criteria.
- September - November 2024: MPCA reviews of public comments and revises permit.
- Dec. 18: Second draft permit is released and a 45-day public comment period begins
- Jan. 22, 2025: Virtual public information session
- Feb. 3: Public comment period closes. MPCA considers comments as final permit is prepared.
Site history
- 1951: 3M begins commercial production of PFOA in Cottage Grove. More types of PFAS would follow.
- 2002: 3M reports PFAS detections in groundwater at 3M Cottage Grove.
- 2003: MPCA issues a wastewater permit.
- 2004: PFAS is found in drinking water in parts of Washington County.
- 2005: MPCA’s “PFCs at the 3M Cottage Grove site” investigation begins.
- 2007: A consent order, still in place today, commits 3M to PFAS remediation measures and drinking water protection for impacted communities.
- 2010: The State of Minnesota sues 3M for natural resource damages from PFAS pollution in the East Metro.
- 2011: MPCA work on a new wastewater permit is paused due to the lawsuit.
- 2018: 3M settles the natural resource damages lawsuit for $850 million.
- 2020: As a result of information received, the MPCA opens a new investigation at 3M Cottage Grove. This investigation is ongoing.
- 2021: 3M Cottage Grove is fined $80,000 and required to take protective measures due to mishandling of hazardous waste.
- 2022: 3M Cottage Grove is fined $2.8 million and required to take corrective measures due to mishandling of hazardous waste.
- Feb. 2024: 3M pays a $4,165 penalty and agrees to corrective action for mishandling hazardous waste.
- May 2024: MPCA issues site-specific water quality criteria for miles 812 to 820 of the Mississippi River.