Wisconsin Enacts 4 ppt PFAS Limits and $125M Clean-Up Bill with Innocent Landowner Protections

Overview

A landmark regulatory shift in the United States has redefined the legal and financial frameworks governing legacy per- and polyfluoroalkyl substances (PFAS) contamination. The State of Wisconsin has adopted some of the most stringent drinking water limits in the world through amendments to its administrative code, while a parallel legislative push to establish a major funding mechanism and targeted liability relief has stalled amid a high-profile veto dispute. The unresolved political fight over how to pair aggressive environmental standards with statutory protections for blameless property owners illustrates the commercial bottlenecks that typically occur when persistent chemicals are discovered on commercial and industrial land.

For Australian property developers, commercial lawyers, local councils, and environmental consultants, these international developments provide a critical case study. Historically, Australian environmental policy has been heavily influenced by regulatory trends in North America and Europe. As international criteria continue to tighten, local practitioners must anticipate how these microscopic compliance thresholds will affect liability, site assessments, and transaction risk. The debate over an innocent landowner exemption overseas highlights a significant policy gap in Australian state-based legislation, where the financial burden of historical contamination often defaults to the current owner regardless of fault.

This development is particularly relevant as Australian environmental regulators, including the Heads of EPAs Australia and New Zealand, prepare to finalise more restrictive guidelines for persistent organic pollutants. By understanding the administrative mechanics of the Wisconsin reforms, Australian professionals can better advise clients on the long-term risk profile of contaminated land portfolios, the evolution of environmental due diligence, and the technical defensive measures required during groundwater investigations.

Wisconsin’s Ultra-Low PFAS Limits

The regulatory changes in Wisconsin are driven by two main components: amendments to the state administrative code governing water quality, and a separate, unresolved legislative effort to fund clean-up and provide liability protections. Under the amended Wisconsin Administrative Code chapter NR 809, the state has established Maximum Contaminant Levels for drinking water that target specific PFAS compounds. Most notably, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are now capped at an ultra-low threshold of 4 parts per trillion (0.004 micrograms per litre [microg/L]). This standard matches the federal limits set by the United States Environmental Protection Agency, marking a significant drop from previous state health advisory levels.

In addition to PFOA and PFOS, the administrative code regulates three other PFAS compounds: perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX). These three additional compounds are subject to an individual limit of 10 parts per trillion (0.01 micrograms per litre [microg/L]). To address the cumulative risks associated with complex chemical mixtures, the state has adopted a formal hazard index approach. This mathematical methodology calculates the ratio of each detected PFAS compound against its individual health-based advisory limit, summing the ratios to determine whether the total mixture poses an unacceptable health risk, even if individual compounds remain below their respective caps.

The $125M Funding and Liability Dispute

To facilitate compliance and mitigate the economic impact of these stringent limits, the Wisconsin Legislature passed Senate Bill 312 (and its companion Assembly Bill 312) during the 2023-24 session, authorising a USD 125 million (approximately AUD 190 million) funding package. The fund was designed to assist municipal water suppliers, local government authorities, and private landowners with the costs of testing, water filtration infrastructure, and soil and groundwater remediation. The funding package was paired with an innocent landowner exemption, a statutory provision intended to shield property owners from state enforcement actions, clean-up orders, and cost-recovery claims if they could demonstrate that the PFAS contamination originated from an off-site source or was historically deposited by a third party prior to their acquisition of the land.

However, Governor Tony Evers vetoed the bill in April 2024, arguing that the liability protections were too broad and would effectively shield genuine polluters from accountability. As a result, the USD 125 million allocation remains unspent in a state trust fund, and the innocent landowner exemption has not been enacted into law. The standoff between the legislature and the governor’s office has left municipalities and landowners without access to the dedicated funding stream, even as the new drinking water limits take effect.

Had it been enacted, the innocent landowner protection would have represented a significant departure from traditional strict, joint, and several liability frameworks. Under the proposal, landowners would have needed to meet specific criteria to qualify, including providing access to the regulatory authorities for sampling, cooperating with ongoing remediation efforts, and demonstrating that they did not contribute to the release or migration of the substances. Supporters argued the mechanism was necessary to prevent the abandonment of commercial brownfield sites and to ensure that the discovery of microscopic PFAS concentrations did not permanently freeze real estate transactions or bankrupt good-faith purchasers.

Australian context

In Australia, the assessment and management of contaminated land are governed by a complex matrix of federal guidelines and state-based legislation. The primary technical framework is the National Environment Protection (Assessment of Site Contamination) Measure 1999, commonly referred to as the NEPM 2013 revision. PFAS management is further detailed in the PFAS National Environmental Management Plan (PFAS NEMP), with version 3.0 currently in development to address emerging scientific data. Comparing Wisconsin’s 0.004 micrograms per litre (microg/L) threshold to current Australian guidelines reveals a substantial regulatory gap. The current Australian drinking water guideline value, established by the National Health and Medical Research Council, is 0.07 micrograms per litre (microg/L) for the combined concentrations of PFOS and PFHxS, and 0.56 micrograms per litre (microg/L) for PFOA. This means Wisconsin’s new limits are more than an order of magnitude lower than the current Australian drinking water standards.

References and related sources

• Primary source: www.wisbar.org
• PFAS National Environmental Management Plan (NEMP)
• NEPM Assessment of Site Contamination
• Australian Drinking Water Guidelines

How iEnvi can help

iEnvi provides specialist consulting services relevant to this topic. Our team includes CEnvP Site Contamination Specialists with experience across contaminated land, groundwater, remediation, ecology, and regulatory compliance.

• iEnvi groundwater services
• iEnvi remediation and validation services
• iEnvi expert services and independent review services

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This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.

Published: 17 Jun 2026

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