Wisconsin Supreme Court holds that DNR has authority to address PFAS contamination without first promulgating rules identifying each contaminant as a “hazardous substance”
Introduction
On June 24, 2025, the Wisconsin Supreme Court issued a landmark environmental decision in Wisconsin Manufacturers & Commerce, Inc. v. DNR. The Court concluded that the Department of Natural Resources (“DNR”) has the authority to require the cleanup of “emerging contaminants,” like PFAS, without first promulgating rules identifying each substance qualifying as a “hazardous substance” under Wis. Stat. § 292.01(5), a provision in the state “Spills Law.” The Spills Law, Wis. Stat. § 292.01 et seq., regulates the discharge of hazardous substances and requires a person who possesses or controls a hazardous substance or who causes the discharge of a hazardous substance to report and remediate the discharge.
In this dispute, a cleaning company, Leather Rich, had discovered that its property was contaminated with two PFAS chemicals and initially reported the discharge to DNR and worked to remediate the property. Eventually, the company ceased remediation efforts and sued DNR, with other interested parties, arguing that DNR could not rely on the Spills Law to force Leather Rich to clean up the contamination related to PFAS compounds without having promulgated an administrative rule identifying the PFAS substances as hazardous substances under the Spills Law.
Background
The stakes of the decision were high. DNR argued that the language of the Spills Law provides broad authority to regulate hazardous substances. Further, the agency argued that promulgating rules identifying each hazardous substance under the Spills Law before requiring a responsible party to comply with cleanup measures would hamstring the agency’s ability to respond effectively to hazardous substance spills, which often depend on quick action to protect people and the environment. The promulgation of rules can take years, and if DNR had to promulgate a rule each time it identified a substance as “hazardous” before taking action, polluters would be allowed to discharge hazardous substances “without any responsibility to begin remediation” in the interim. DNR argued that such a requirement would be especially onerous for emerging contaminants—as there are thousands of PFAS compounds and mixtures, with new substances still being created—and the agency’s ability to tackle PFAS contamination would be severely limited.
On the other hand, WMC argued that the agency must promulgate rules listing each hazardous substance to which the Spills Law applies because citizens have the right to know whether the Spills Law applies to their discharge, prior to expending time and money remediating it. As part of its argument, WMC contrasted rules and guidance documents: an unpromulgated rule is invalid and unenforceable, but a “guidance document” is merely intended to explain a statute or rule and does not have legal effect. DNR had made statements on its website and in letters to responsible parties that emerging contaminants are “hazardous substances” which WMC argued are invalid unpromulgated rules. DNR argued these communications were merely guidance documents.
Analysis
In the majority opinion authored by Justice Protasiewicz, the Court addressed three issues. First, it looked at three provisions in Wis. Stat. ch. 227, Wisconsin’s Administrative Procedure and Review Act, to assess whether these provisions require DNR to promulgate rules before applying the Spills Law in certain situations. Second, the Court addressed whether DNR must promulgate rules before stating on its website or in letters that emerging contaminants like PFAS satisfy the definition of “hazardous substance” under the Spills Law or whether such statements are guidance documents. Finally, the Court examined whether DNR may enforce a threshold for reporting a discharge of emerging contaminants. On each issue, the Court ruled in DNR’s favor.
The Court rejected WMC’s argument that the phrase “hazardous substance,” as defined in Wis. Stat. § 292.01(5), is ambiguous and that DNR needed to promulgate each “hazardous substance” individually as a rule before applying the law. The Court concluded that although the phrase was broad, it was unambiguous, and DNR’s statements—that PFAS and other emerging contaminants constitute hazardous substances—exemplify the agency “applying an unambiguous statute to a new set of facts.” The Court also noted that that Wis. Stat. § 292.01(5) “imposes no rulemaking requirement upon the DNR” and that, in contrast to several other provisions of the Spills Law, such a requirement is “conspicuously absent” in this section.
The Court also clarified the difference between guidance documents and rulemaking, concluding that the DNR’s statements (both in letters to responsible parties and on its website) are “communications about the law” but “not the law itself.” The Court concluded that these statements merely provide advice on how the agency is likely to apply the Spills Law, but do not provide authority for implementing or enforcing the law. Thus, these statements need not follow the rule promulgation process.
Finally, the Court determined that DNR may enforce a threshold for reporting emerging contaminant discharge without promulgating that threshold as a rule. The opinion notes that the Spills Law gives the agency “broad but explicit authority” to enforce a threshold for reporting a PFAS discharge without promulgating a rule, acknowledging that the statute is wide-reaching (applying to “any substance or combination of substances”) but not all-encompassing. Notably, it explicitly requires the substances to first satisfy the provision’s fact-specific criteria, including the quantity, concentration, physical, chemical or infectious characteristics of the substance that make it hazardous.
The decision marks an important win for DNR and environmental advocates. Attorney General Josh Kaul issued a statement on the outcome, noting that a contrary ruling “would have significantly weakened our Spills Law.”
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