Property owners suing 3M, BASF and the former and current owners of the Rhinelander paper mill over PFAS contamination in the Town of Stella have asked a federal judge to certify their case as a class action lawsuit, a move that could let the property owners in the affected area pursue their claims together rather than filing individual lawsuits.
The motion, filed Aug. 25 in the U.S. District Court for the Western District of Wisconsin, asks the court to certify a property-damage class made up of owners of real property within a defined area of Oneida County where fibercake from the Rhinelander mill was land-applied. The plaintiffs allege the land application resulted in contaminated groundwater, private wells and connected surface waters.
The filing comes roughly a year after the Department of Natural Resources formally notified 3M, BASF, Ahlstrom and Wausau Paper/Essity that it had designated them as responsible parties for the contamination, following a 2022 DNR sampling project that found some of the highest PFAS levels recorded in the country in the rural township.
PFAS (per- and polyfluoroalkyl substances) are a large group of manmade chemicals used since the 1940s to make products resistant to water, grease, and stains — think nonstick cookware, waterproof fabrics, food packaging, and firefighting foam. They’re often called “forever chemicals” because their carbon-fluorine bonds are extremely strong and don’t break down naturally, so they persist in the environment and can accumulate in the human body.
Named as defendants are 3M Company; BASF Corporation (formerly Ciba-Geigy, which later became Ciba Specialty Chemicals); Wausau Paper, which owned and operated the Rhinelander mill until 2013; and Ahlstrom, the mill’s current owner.
Proposed subclasses
Rather than treating every property in the class area identically, plaintiffs’ attorneys have proposed three subclasses tied to different ways the contamination reached individual properties:
Groundwater/Private Well Subclass, for owners whose primary drinking water source is a private well affected by PFAS-contaminated groundwater.
Sludge Application Subclass, for owners of properties where mill fibercake was directly spread.
Surface Water/Riparian Subclass, for owners of property adjacent to or with riparian rights in Snowden Lake, the Moen Lake chain, Starks Creek or the North Branch of the Pelican River.
According to the plaintiffs’ supporting memorandum, roughly 87 parcels received direct land application of fibercake, about 307 parcels fall within mapped PFAS groundwater plume areas, and approximately 642 parcels are considered riparian to affected waterways. The filing states more than 100 people are believed to be part of the proposed class overall.
Well contamination figures
The memorandum cites DNR groundwater sampling from 2022 and 2023 showing PFOA detected in private wells in the area at concentrations up to 50,000 parts per trillion — well above the U.S. Environmental Protection Agency’s maximum contaminant level of 4 ppt — and PFOS detected up to 7,980 ppt, against the same 4 ppt limit. Surface water samples from Snowden Lake showed PFOA concentrations up to 1,770 ppt, exceeding state surface water quality standards, according to the filing.One of the proposed new sludge-application subclass representatives has a private well testing at 715 ppt for PFOA and 42.2 ppt for PFOS, per a declaration cited in the brief.
Plaintiffs’ argument for certification
To win certification, plaintiffs must show the proposed class meets several requirements including numerosity, commonality, typicality, adequacy of representation, predominance and superiority. Plaintiffs argue in the alternative that if the court won’t certify the full class, it should at least certify a narrower set of “core” common issues, such as whether PFAS from 3M and BASF products entered the mill’s wastewater and sludge, and whether land application of that sludge caused the contamination.
The brief argues the case is built on common evidence: a single mill, using PFAS-containing products supplied over the decades by 3M and Ciba/BASF, that ran a consistent sludge and fibercake land-spreading program from the 1990s through 2025 under the oversight of an environmental control manager. Plaintiffs contend 3M and Ciba/BASF knew or should have known their fluorochemical products were persistent, mobile and unsuited to land application, and that the companies didn’t adequately warn the mill, while the mill continued spreading fibercake despite manufacturer safety-sheet changes calling for more restrictive disposal.
The filing includes information gleaned from depositions taken from multiple individuals who were involved in the day-to-day administration of the mill’s land spreading program from the 1990s to 2025.
It also leans on the DNR’s findings. It quotes language from the DNR’s 2025 “responsible party” letters to Wausau Paper/Essity and Ahlstrom rejecting the argument that mill’s discharge permits shielded it from liability, stating that no permit issued to the mill authorized the discharge of PFAS.
Plaintiffs also point to a damages methodology proposed by real estate valuation expert Dr. Michael Tachovsky, who the brief says used a mass-appraisal approach — combining remediation costs, impairment of use and market stigma — to model property value diminution, and applied it on a trial basis to four class properties.
The certification motion follows years of state and federal scrutiny of the Stella area. DNR sampling beginning in 2022 found extremely high PFAS levels in private wells. Last year, DNR sent formal “responsible party” letters to Ahlstrom and Wausau Paper/Essity, and the Stella area remains under EPA review for potential inclusion on the Superfund National Priorities List. The DNR has also issued fish and deer consumption advisories for parts of the area, including a “do not eat” advisory for fish from several area lakes.
Attorneys for the defendants have until late October to file their written responses to the motion and the Star Journal expects to report on those filings at that time. Prior to publication of this article, we reached out to Ahlstrom to offer an opportunity to comment on the motion. “It is Ahlstrom’s policy not to provide comment on pending litigation,” spokesperson Tricia Schwartz replied. Since the litigation began, Ahlstrom officials have repeatedly stressed that the Finnish-based company did not purchase the Rhinelander mill until 2018. The company also claims it has not used PFOA or PFOS in the Rhinelander mill's manufacturing process.
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