Investigation
40 Years of Contamination:
The Wausau Superfund Story
In 1982, the city of Wausau, Wisconsin discovered that three of its six municipal wells were poisoned with industrial solvents. More than four decades later, the contamination is still unfolding — and now it's a different chemical entirely.
Poison in the tap water
In the spring of 1982, routine testing found in City Well #3, east of the Wisconsin River.
By summer, City Well #6 on the west side tested positive for , , and other solvents.
By fall, a third well — City Well #4 — showed contamination too. Three of the six wells serving roughly 35,000 people were now compromised.
Emergency filters go in
The EPA awarded the City of Wausau a federal grant to install at the contaminated wells.
This was a stopgap. It treated the water coming out of the tap, but the contamination was still spreading underground.
EPA declares emergency response
Chemical levels stayed dangerously high despite the air strippers. The EPA's emergency response team was called in.
They installed a temporary treatment system on City Well #6.
The federal government takes notice
On April 10, 1985, the EPA proposed the Wausau Ground Water Contamination site for the .
In December, the EPA sent a formal letter to Wausau Chemical Corporation, notifying them that their facility was a source of the contamination and requesting they begin cleanup under federal .
Officially one of America's most contaminated sites
On June 10, 1986, the site was formally added to the NPL. Investigators identified three contamination sources:
A former municipal landfill on the Marathon Electric Corporation property, along the west bank of the Wisconsin River — the primary source of TCE in the groundwater.
The Wausau Chemical Company facility on the east bank — contaminated primarily with PCE and other industrial solvents.
The Wausau Energy Company — a third contributor to the underground contamination plume.
Mapping the damage, writing the cleanup plan
From August 1987 to September 1988, the EPA conducted a two-phase to map the full extent of contamination underground.
In December 1988, the EPA issued an interim calling for a pump-and-treat system to pull contaminated groundwater out and clean it.
The final ROD was signed in September 1989. The full cleanup included extraction wells with treatment systems, two soil vapor extraction systems, a cap over the landfill waste, restrictions on land and groundwater use, and ongoing monitoring.
Off the list — but not clean
The EPA transferred cleanup responsibility to the and removed the site from the National Priorities List.
This didn't mean the ground was clean. It meant the cleanup had moved from emergency mode to long-term containment and monitoring. The contamination was still underground — and would stay there.
"Complete cleanup is impractical"
In its , the EPA stated that complete remediation of soils beneath the Wausau Chemical building is “impractical.”
The contamination had been there for so long, and gone so deep, that fully removing it was no longer considered feasible. The strategy shifted permanently to containment — keeping the chemicals from spreading further, rather than taking them out.
A contaminated riverbank in a flood zone
A U.S. Government Accountability Office report identified the Wausau Superfund site as one of 23 in Wisconsin vulnerable to flooding.
A site full of buried industrial solvents, sitting on the banks of a major river, in a state seeing increasingly severe storms. If floodwaters reach the contaminated soil, they can carry those chemicals into the river and spread contamination well beyond the original site boundaries.
New treatment plant — for a new contaminant
Forty years after VOCs were first discovered, a different class of chemicals emerged: , also known as “forever chemicals.”
Unlike VOCs, PFAS don't evaporate. They don't decompose. And they accumulate in human tissue over time. Health researchers have linked long-term exposure to kidney and testicular cancer, thyroid disease, high cholesterol, immune system disruption, and pregnancy complications.
In December 2022, Wausau brought a new treatment plant online using a temporary anion exchange resin system. It worked — but cost about $800,000 per year to operate.
PFAS in the employees' water. The city sues.
In November 2023, high levels of PFAS were discovered in the water that 3M employees were drinking at the company's own Wausau facility.
In December, the City of Wausau filed a federal lawsuit against 15 chemical manufacturers — including 3M and DuPont — and 61 insurance companies.
Water rates had already jumped 65% to cover the new treatment systems. Wausau's residents were footing the bill for contamination they didn't cause.
$17 million filtration system. Water bills double.
The city completed a $17 million granular activated carbon filtration system — the permanent solution to PFAS in the drinking water. It reduced PFAS to non-detectable levels.
But someone had to pay for it. The average annual water bill climbed from about $229 in 2021 to about $448 in 2024. For 40,000 residents, water now costs nearly twice what it did three years earlier.
In December, private well owners living near the 3M Greystone quarry filed a , seeking property damages and medical monitoring costs.
3M's own site is contaminated. The state steps in.
In February, 3M's environmental consultant reported a of PFAS at the Greystone site to the Wisconsin Department of Natural Resources.
In March, the DNR issued a formal to 3M — the first in Marathon County tied solely to PFAS contamination.
In October, Wausau received $2.86 million from 3M as part of a broader multi-district settlement. The city planned to use the funds to ease pressure on water rates.
In December, test results from a monitoring well inside a former disposal zone at Greystone came back: at 3,700 nanograms per liter. Wisconsin's proposed limit is 4 ng/L. That's 925 times over.
The fallout is just beginning
Testing has confirmed that PFAS has polluted groundwater across large sections of the Greystone property. Stormwater basins on the east side of the site, near the Wisconsin River, also tested far above state limits.
3M's environmental consultant submitted a site investigation work plan to the DNR in April 2026. The investigation is active and ongoing.
In May, Wisconsin received $15 million in federal PFAS funding for drinking water treatment — but communities near Wausau are still building treatment systems.
The class action lawsuit by private well owners is heading toward a 2027 trial.
By the numbers
44
years since contamination first detected
$17M
cost of permanent PFAS filtration
925×
over proposed state limit at 3M Greystone
40,000
residents affected by doubled water bills
Why this is on a fishing technology website
Nemo's Eye was born on this river. The founder grew up fishing the Wisconsin River in central Wisconsin — the same water sitting on top of this Superfund site.
Nemo's Eye builds drop-in smart probes that measure water quality in real time. The sporting product helps anglers make better decisions on the water. But the same technology, deployed at scale, creates a distributed monitoring network that catches contamination problems early — before they take four decades and tens of millions of dollars to address.