PFAS―the Forever Chemical and Carcinogen―in Our Door County Water
By Mike Bahrke
Per- and polyfluoroalkyl substances (PFAS) are long-lasting "forever chemicals" used since the 1940s in non-stick cookware, water-resistant fabrics, food packaging, and firefighting foam. They have been found to contaminate water, soil, and food, leading to widespread human exposure. This exposure has been linked to cancer, liver damage, reduced fertility, and developmental issues.
Across the bay of Green Bay, in the Marinette and Peshtigo areas, as early as 2013, PFAS contamination was discovered in soil, sediment, groundwater, surface water, private drinking water wells, and bio solids by Johnson Controls (an American-Irish multinational conglomerate headquartered in Cork, Ireland that produces fire, HVAC, and security equipment for buildings). In January 2016, Johnson Controls announced a merger with Tyco International (which included the Ansul fire suppressant business in Marinette, WI) to form Johnson Controls International, PLC. The PFAS found there has been primarily linked to the firefighting foam produced by the Tyco Fire Technology Center. Public awareness and widespread investigation began in late 2016 and 2017, when PFAS was identified in private wells near the Tyco boundaries. Testing and mitigation, including providing bottled water, have continued from 2017 to the present time.
While some believed the primary threat of PFAS in Door County would come from Marinette and Peshtigo roughly 15-20 miles across the bay from Door County), the PFAS present in Door County originates from various human-made sources, including firefighting foam, consumer product waste, and the application of treated municipal bio solids (sludge) on farm fields, which can leak into groundwater. While major plumes of pollution are documented nearby in Marinette and Peshtigo, Door County's surface activities, thin soil, and karst geology make groundwater in Door County highly susceptible to the spread of contaminants into drinking water wells. Unbeknownst to many, Door County has been actively monitoring PFAS (per- and polyfluoroalkyl substances) in groundwater due to the area’s vulnerable fractured bedrock geology, with studies ongoing since early 2024. And while localized areas of concern have been tested, broad, alarming contamination has not been widely reported. Meanwhile, the County has joined lawsuits against the sources of PFAS. In April 2026, the Door County Board of Supervisors approved joining multi-district litigation against PFAS manufacturers (such as 3M and DuPont) to hold them responsible for contamination in Door County. On the state level, Wisconsin has witnessed widespread PFAS issues, with the state Senate recently passing legislation to allocate over $133 million for PFAS cleanup.
The Door County Soil and Water Conservation Department, in collaboration with GZA GeoEnvironmental, and UW-Oshkosh, has been sampling private wells for PFAS, nitrates, and other contaminants since 2024, with further sampling scheduled for spring and fall 2026. While initial results have revealed few areas of major concern, testing has been focused on specific localized areas and the number of samples tested has been small.
In summary, PFAS are present in Door County. They come from multiple sources, and while well testing has yet to reveal areas of major concern in Door County, methodological limitations such as small sample size (approximately 400 (~5%) of the 8,000 private wells in Door County were sampled/tested in 2024), nonrandom sampling (testing is voluntary and geographically clustered) and a lack of test-retest sampling/testing have significantly limited the validity, reliability, and conclusions of past sampling and testing.
Additional information on known PFAS contamination sites can be found on the Wisconsin DNR PFAS Interactive Data Viewer.