Eau Claire — French for “clear water” — is named for the river that runs through it. The irony isn’t lost on residents who’ve been following Wisconsin’s growing PFAS contamination crisis and wondering what’s really in their water.
PFAS: Wisconsin’s Statewide Problem Hits Home
Wisconsin has been one of the most aggressive states in the nation when it comes to PFAS testing and regulation. The Wisconsin Department of Natural Resources (DNR) has identified PFAS contamination at dozens of sites across the state, and Eau Claire hasn’t been spared.
Sources of PFAS contamination in the Eau Claire area include:
Airport firefighting foam — Chippewa Valley Regional Airport, like airports nationwide, used AFFF (aqueous film-forming foam) for firefighting training and emergency response. AFFF is one of the most significant sources of PFAS contamination nationally. Testing near airports across Wisconsin has consistently found PFAS in groundwater.
Industrial sources — Eau Claire’s manufacturing history includes metalworking, paper manufacturing, and other industries that used PFAS-containing products in their processes. These facilities can contribute PFAS to groundwater through wastewater discharge, spills, and waste disposal.
Biosolids application — the land application of treated sewage sludge (biosolids) from wastewater treatment plants is an emerging concern in Wisconsin. Biosolids can contain PFAS that entered the sewer system from industrial and residential sources, and spreading these materials on agricultural land can contaminate soil and groundwater.
Wisconsin has established some of the most protective PFAS groundwater standards in the country:
- Combined PFOA/PFOS: 20 parts per trillion (groundwater enforcement standard)
- The state continues to evaluate additional PFAS compounds for regulation
The Chippewa River Watershed
Eau Claire sits at the confluence of the Chippewa and Eau Claire rivers. The Chippewa River watershed — one of the largest in Wisconsin at over 9,500 square miles — drains a landscape that’s a mix of forests, agriculture, and small towns.
Water quality in the watershed is affected by:
- Agricultural runoff — dairy farming and crop production in the Chippewa Valley contribute nutrients (nitrogen and phosphorus), sediment, and pesticides to surface water
- Phosphorus loading — Wisconsin has struggled with phosphorus pollution in its waterways, driving algal blooms in lakes and rivers. The Chippewa River carries phosphorus loads from upstream agricultural areas.
- Chloride from road salt — winter salt application on roads is increasingly recognized as a freshwater pollution source in Wisconsin. Chloride levels in many Wisconsin waterways have been rising steadily.
- Logging and development — changes in land use affect runoff patterns, erosion, and the watershed’s natural filtering capacity
Municipal Water: Groundwater-Based System
Unlike many cities that draw from surface water, Eau Claire’s municipal water supply comes primarily from groundwater wells drawing from the sandstone aquifer system beneath the Chippewa Valley.
This groundwater source has advantages:
- Natural filtration — water that has percolated through hundreds of feet of rock and sediment is generally well-filtered
- Consistent quality — groundwater is less susceptible to seasonal changes that affect surface water
- Lower treatment needs — groundwater typically requires less treatment than surface water
But groundwater systems also face specific risks:
- PFAS contamination — once PFAS reaches groundwater, it persists and can migrate through aquifer systems
- Nitrate infiltration — agricultural activity above the aquifer contributes nitrates that can reach drinking water wells
- Naturally occurring contaminants — Wisconsin’s sandstone aquifers can contain naturally elevated levels of radium, arsenic, and manganese
The Eau Claire water utility regularly tests for all regulated contaminants and publishes results in its annual water quality report.
Radium in Wisconsin Groundwater
One contaminant that’s particularly relevant to groundwater-dependent communities in Wisconsin is radium. Naturally occurring radioactive materials in the sandstone aquifer systems that supply much of Wisconsin’s drinking water can produce radium at levels approaching or exceeding the EPA’s maximum contaminant level of 5 picocuries per liter (combined radium-226 and radium-228).
Several Wisconsin communities have been required to install treatment systems specifically for radium removal. While Eau Claire’s levels have generally been within compliance, the issue underscores the importance of ongoing monitoring for naturally occurring contaminants.
Private Wells in Eau Claire County
About 30% of Wisconsin residents rely on private wells, and Eau Claire County is no exception. Rural residents outside the municipal water service area face their own set of challenges:
- Nitrate contamination — agricultural areas in the county have documented nitrate levels exceeding the 10 mg/L health standard in some private wells
- Bacteria — shallow wells and wells with compromised casings can be vulnerable to bacterial contamination, particularly in areas with sandy soils and high water tables
- PFAS — private wells near known contamination sites may be at risk. Wisconsin DNR offers free PFAS testing for wells near identified contamination areas.
- Arsenic — naturally occurring arsenic in some Wisconsin aquifer formations can affect private wells
Wisconsin requires well testing for bacteria and nitrate when a new well is constructed, but there’s no requirement for ongoing testing. The Wisconsin DNR recommends annual testing for bacteria and nitrate, and periodic testing for other contaminants based on local conditions.
What Residents Can Do
- Review your water quality report — Eau Claire’s utility publishes annual results that detail every tested contaminant
- Test your private well — if you’re on a well, test annually for bacteria and nitrates at minimum. Consider PFAS testing if you’re near airports, industrial sites, or agricultural land where biosolids have been applied.
- Check Wisconsin DNR’s PFAS map — the state maintains a public database of known PFAS contamination sites
- Consider treatment — reverse osmosis is effective for PFAS, nitrates, and radium. Activated carbon can address PFAS and many organic contaminants.
- Stay informed — Wisconsin’s PFAS regulatory landscape is evolving rapidly
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions specific to western Wisconsin’s groundwater challenges.