Wisconsin now has enforceable groundwater limits for “forever chemicals.” On October 28, the Wisconsin Natural Resources Board (NRB) voted unanimously to adopt Board Order DG-02-25, which amends chapter NR 140 of the Wisconsin Administrative Code to add numeric standards for six per- and polyfluoroalkyl substances (PFAS). Gov. Tony Evers signed the rule the same day and announced his approval on October 29, the day on which it was also signed by the DNR deputy secretary.

The action ends a multiyear effort that stalled twice before, and it reaches well beyond drinking water.

The New Numbers

NR 140 uses two tiers. The enforcement standard (ES) sets the level used to establish limits for discharges to groundwater. The preventive action limit (PAL) triggers action to head off further contamination. Under the new rule, each PAL equals 10 percent of the corresponding ES. The rule tracks recommendations the Wisconsin Department of Health Services (DHS) issued in 2025, which DHS based largely on EPA’s 2024 federal drinking water limits.

One part per trillion equals one nanogram per liter.

These groundwater standards stand apart from the PFAS drinking water limits the state adopted earlier this year, which lowered the PFOA and PFOS threshold for public water systems from 70 ppt to 4 ppt. The drinking water rules govern what public systems deliver at the tap. The NR 140 standards, by contrast, apply across DNR programs, including discharge permitting, monitoring, corrective action, and contaminated-site cleanups. That breadth gives the new rule its reach.

Roughly 70 percent of Wisconsin residents, and 95 percent of its communities, depend on groundwater for drinking water. DNR sampling in 2022 found at least one PFAS compound in 71 percent of 450 private wells tested, and an estimated 32,000 private wells may exceed the new standards.

Remediation Sites Face New Cleanup Targets

The biggest near-term shift may come at contaminated sites. Until now, the DNR has addressed PFAS in groundwater by setting site-specific cleanup standards under Wis. Admin. Code § NR 722.09(2)(b)2. Once the NR 140 standards take effect, NR 722.09(2)(b)1. makes the PAL the groundwater restoration goal to be met to the extent technically and economically feasible. For PFOA and PFOS, that goal sits at 0.4 ppt.

The ES values will also feed the calculation of groundwater-protective soil residual contaminant levels under NR 720.10, so soil cleanup obligations may tighten as well. Responsible parties with open cases should expect the DNR to revisit:

• whether existing investigations fully delineate the PFAS plume under the new benchmarks;
• remedy selection, cost estimates, and long-term monitoring plans; and
• case closure requests under chapter NR 726, which will remain site-specific determinations.

The DNR has not explained how it will treat cases already in progress or previously closed. That transition guidance will drive much of the real-world cost.

Permittees, Landfills, and Biosolids

Industrial dischargers, municipal wastewater treatment plants, and landfill operators should anticipate added PFAS sampling and monitoring as permits come up for renewal or modification. Where groundwater monitoring shows PAL or ES exceedances, the DNR may require further investigation, response actions, or changes in waste management.

Biosolids present a particular pressure point. Many Wisconsin utilities land-apply sludge, a practice that can carry PFAS into soil and shallow groundwater. Those utilities may need to shift to landfilling or incineration, which carry their own costs, discussed below.

Compliance Costs and the REINS Act

Cost has shaped this rule from the start. Wisconsin’s REINS Act requires legislative approval of any rule expected to impose more than $10 million in implementation and compliance costs over a two-year period. A prior groundwater rulemaking stopped in 2023 after its cost estimate crossed that line. The DNR withdrew a later proposal in February 2025 and began the current rulemaking that same month.

The Broader Regulatory Landscape

Wisconsin joins Minnesota, Michigan, Illinois, and Iowa in setting PFAS groundwater standards. Illinois adopted identical enforcement-level values for the same six compounds in March 2025. Federal footing remains less certain: EPA has announced plans to reconsider parts of its 2024 drinking water rule, and utilities and chemical companies continue to litigate it. Because DHS built its recommendations on the federal limits, any federal retreat could prompt calls to revisit Wisconsin’s numbers, but the state standards stand on their own unless and until the state amends them. At the same time, Wisconsin has opened its PFAS Trust Fund for sampling programs, including community grants and free private well testing, which will likely surface more detections.

Wisconsin’s new environmental legislation marks a significant change in Wisconsin’s groundwater framework. Its practical effect will turn on how the DNR applies it to existing permits and open cases, and on site-specific conditions. The Environmental Law Monitor will continue to follow developments.