Court of Appeals Reverses Two Discrete Elements of 3M NPDES/SDS Permit

Originally published in the September 2026 issue of Bench & Bar of Minnesota Environmental Law Update, Minnesota State Bar Association.

In an unpublished opinion dated June 8, 2026, the Minnesota Court of Appeals reversed and remanded two discrete aspects of the June 1, 2025, NPDES/SDS wastewater discharge permit (Permit) the Minnesota Pollution Control Agency (MPCA) issued to Chemical Operations LLC (3M) for 3M’s Cottage Grove manufacturing facility. In Re the Final NPDES/SDS Permit for 3M Cottage Grove Center, A25-1049, 2026 WL 1647811 (Minn. Ct. App. June 8, 2026).

The Permit was notable because it included first-time numeric effluent limits for five PFAS compounds — PFOS, PFOA, PFHxS, PFBS and PFBA. For several of these PFAS, the effluent limit is set below the current laboratory detection limits, so MPCA included temporary, less stringent “compliance limits” in the Permit. The limits were based on site-specific PFAS water quality standards in the Mississippi River for Class 2B and Class 2 fish tissue. To meet these requirements, 3M must, by April 2027, implement an advanced wastewater treatment system that may include reverse osmosis, granular activated carbon (GAC), and ion exchange (IX) technologies.  

3M’s appeal challenged three aspects of the Permit: (1) PFAS-testing requirements, (2) PFAS laboratory accreditation requirements, and (3) a thermal-load condition. Each of these is discussed below.

PFAS-Testing Requirements

Regarding the Permit’s PFAS-testing conditions, 3M argued that MPCA’s decision to require 3M to sample and analyze110 PFAS analytes was unsupported by substantial evidence in the record. The 110 PFAS analytes fell into three categories: (1) 38 analytes that EPA’s standard PFAS testing methodology, Method 1633, can reliably detect, (2) 56 analytes that cannot be reliably detected by Method 1633 but can be detected by existing methods other than Method 1633, and (3) 16 analytes for which there is currently no existing test method. 3M disputed MPCA’s authority to impose testing for categories two and three. Regarding category 2, the court held that MPCA had sufficiently considered the problem and addressed it by, e.g., saying MPCA will accept any methods “equivalent to” or “better than” Method 1633, including certain internal 3M testing methods. However, for Category 3, the 16 analytes for which there currently is no known testing method, the court held that the lack of a testing method meant MPCA’s requirement to test the analytes was unsupported by substantial evidence. MPCA clarified that MPCA could impose other types of conditions for these analytes, such as requiring 3M to pursue methods for testing these analytes, and that once methods are available, MPCA could require testing. 

The court upheld two related challenges to the Permit’s PFAS-testing requirements, largely based on principles of deference. First, the court rejected 3M’s argument that requiring testing with methods other than Method 1633 was not “appropriate” under Minn. R. 7001.1060, subp. 2 (requiring analysis “using techniques found by the commissioner to be appropriate”). This language does not require MPCA to make explicit findings regarding the appropriateness of a testing method, the court held. Second, the court rejected 3M’s argument that MPCA wrongly included testing requirements for 38 PFAS analytes that MPCA has not shown are likely to be present in 3M’s wastewater. The court deferred to MPCA’s bases for its decision, including the uncertainty of testing for new PFAS, 3M's own failure to predict the presence of some analytes, and the future necessity for PFAS-testing requirements.

PFAS Laboratory Accreditation Requirements

Next, the court rejected 3M’s argument that the Permit’s conditions regarding laboratory accreditation were arbitrary and capricious. The Permit states that all data analyses must be conducted by a laboratory accredited by the Minnesota Department of Health and/or certified by the MPCA, unless approved in writing by the MPCA. 3M argued that this imposed the impossible task of applying for accreditation that the state does not offer. The court was unpersuaded, noting that the Permit expressly allows MPCA to approve exceptions, and that MPCA had temporarily waived enforcement of the accreditation provision for the relevant PFAS analytes.

Thermal-Load Condition

Finally, 3M objected to a thermal-load condition in the permit as inconsistent with the U.S. Supreme Court’s March 2025 decision in City of San Francisco v. Environmental Protection Agency, 604 U.S. 334 (2025) (See Supreme Court Rejects Widely Used “End-Result” NPDES Permit Limitations, 03-11-2025). In this decision, the supreme court held that so-called “end result” permit conditions — those that “do not spell out what a permittee must do or refrain from doing” but rather “make a permittee responsible for the quality of the water in the body of water into which the permittee discharges pollutants,” id. at 338 — were not authorized under the federal Clean Water Act. The thermal-load condition in the Permit provided that 3M’s discharge “shall not increase the temperature of the receiving water more than five degrees Fahrenheit above the ambient temperature.” This, 3M argued, was an end-result condition precluded by City of San Francisco. MPCA responded that 3M forfeited this issue because it did not present the issue to MPCA prior to the appeal. MPCA also argued that even if the thermal-load provision did constitute an end-result condition, it was independently authorized under Minnesota law. 

While acknowledging that questions not raised to a lower tribunal generally are forfeited on appeal, citing Thiele v. Stich, 425 N.W.2d 580, 582 (Minn. 1988), the court could make exceptions “as the interest of justice may require.” The court declined to conclude that the thermal-load issue was forfeited and also declined to consider the issue on the merits. Rather, the court held the issue should be remanded to MPCA to address the thermal-load condition and whether it is affected by San Francisco. Notably, the court indicated it saw nothing in the record that MPCA imposed the thermal-load condition pursuant to Minnesota law, so the court did not address this argument. 

The court reversed and remanded this case for MPCA to address the PFAS-testing condition with respect to analytes for which there are no currently available test methods, and the thermal-load condition.

For more information or questions, contact Jeremy Greenhouse.