By Edward B. Witte and Heather Davis
On June 24, 2025, the Wisconsin Supreme Court issued a decision in Wisconsin Manufacturers and Commerce, Inc. v. Wisconsin Department of Natural Resources (2025 WI 26), holding that the Wisconsin Department of Natural Resources (WDNR) has the legal authority to regulate per- and polyfluoroalkyl substances (PFAS) and other emerging contaminants as “hazardous substances” under the Wisconsin “Spills Law” (Wis. Stat. § 292.11)—without first formally engaging in rulemaking to designate them as hazardous. The Court reversed the lower court’s ruling, delivering a significant win for the WDNR against an industry challenge to the state’s forty-year-old cleanup program.
The ruling affirms that WDNR – without first undergoing the time-consuming process of promulgating formal rules – may continue implementing the Spills Law to require parties responsible for, or in control of, hazardous substance discharges to notify the agency and take appropriate cleanup actions.
The plaintiffs challenging WDNR’s actions were Leather Rich, a dry-cleaning company addressing releases of hazardous substances (including PFAS) at its property in Oconomowoc, Wisconsin, and Wisconsin Manufacturers and Commerce (WMC), a statewide business advocacy group.
Leather Rich and WMC argued that WDNR was legally required to engage in rulemaking before taking several specific actions related to the Leather Rich site, including: (a) regulating PFAS as a hazardous substance by confirming it met the Spills Law definition; (b) revising the state’s Voluntary Party Liability Exemption (VPLE) cleanup program to apply more selectively to particular substances or to limited cleanups; and (c) establishing a reportable quantity threshold for PFAS releases.
The Supreme Court rejected these arguments and sided with WDNR. The majority concluded that the Legislature had vested “broad but explicit authority” in the WDNR to regulate hazardous substances, including emerging contaminants like PFAS, under the Spills Law. The opinion includes a detailed evaluation of Wisconsin administrative law, especially Chapter 227 of the Wisconsin statutes, distinguishing between enforceable rules, which require formal rulemaking under Wis. Stat. ch. 227, and guidance documents, which do not carry the force of law but may inform regulated parties.
Notably, the Court emphasized that the Spills Law is “responsible party-driven”—meaning that the legal duty to identify and report hazardous discharges, and to undertake remedial action, falls primarily on the party that is responsible, not on the WDNR. While WDNR retains oversight and discretion, the Spills Law envisions that much of the compliance and cleanup activity occurs without direct agency intervention.
Although the decision is clearly a victory for WDNR, it may also foster greater regulatory certainty for both environmental remediation and economic development in Wisconsin. A decision in favor of the challengers could have introduced significant uncertainty by undermining the legal foundation of the state’s hazardous substance program. While requiring rulemaking might have added clarity to WDNR’s interpretations of the Spills Law, observers of the case noted that such a requirement could have also temporarily destabilized Wisconsin’s longstanding approach to spill response and environmental accountability.
