Waukesha County Circuit Judge Michael Bohren granted a request Tuesday from the Department of Natural Resources to extend the stay while an appeals court reviews his April ruling that the DNR cannot require cleanup of toxic PFAS compounds without first going through a process to define them as hazardous substances.

The ruling was issued in a case brought by the state’s largest business lobby, Wisconsin Manufacturers and Commerce, and an Oconomowoc dry cleaner, which sought to block the DNR from requiring cleanup of the chemicals that have polluted groundwater in sites across the state, including Madison, Marinette and La Crosse.

The plaintiffs claim the DNR is subverting the law by requiring polluters to clean up spills without first defining what substances are hazardous. Bohren agreed but put his ruling on hold so the parties could sort out the implications.

While conceding that extending the stay would harm the plaintiff, he concluded that did not outweigh other concerns in a case likely to end up before the state Supreme Court.

“I’m satisfied it protects everyone’s interests,” Bohren said.

Assistant Attorney General Gabe Johnson-Carp argued that Bohren’s order would upend more than 40 years of the status quo, creating regulatory uncertainty, economic losses and harming families with contaminated wells.

Halting cleanups could also jeopardize about $90 million a year in tax revenue generated by the redevelopment of cleaned-up brownfields.

If the state’s authority were suspended, Johnson-Carp said the federal government could assert its jurisdiction, resulting in slower, more costly cleanups.

Midwest Environmental Advocates argued that lifting the stay would cause irreparable harm to some 1,300 Wisconsin households with polluted wells who would no longer receive bottled water from the DNR.

Those who can’t afford to buy their own would be forced to drink contaminated water or consider moving, the group argued.

The group said Bohren’s order could also stall cleanup efforts, allowing PFAS contamination to spread even further.

WMC attorney Lucas Vebber argued nothing in the order would stop the DNR from carrying out its remediation program or providing bottled water as long as the agency first drafts rules, a 2½-year process subject to approval by the Legislature.

Environmental advocates say that would hamstring the DNR’s authority to stop pollution.

State law requires anyone responsible for spilling a hazardous substance to clean it up under the oversight of the DNR.

But there is no definitive list of hazardous substances, which can include toxic chemicals as well manure, corn, or even milk spilled in a creek — anything “that can cause harm to human health and safety, or the environment, because of where it is spilled, the amount spilled, its toxicity or its concentration.”