Wausau Ground Water Contamination

Overview

The Wausau Ground Water Contamination site sits in northern Wausau, Marathon County, Wisconsin. It has been on the National Priorities List (NPL) since June 1986. The NPL is the EPA's roster of hazardous waste sites that need long-term cleanup. The site is divided into three operable units covering different areas and types of cleanup work. Physical construction of the remedy is complete, but long-term monitoring and maintenance are ongoing.

Three chlorinated solvents are the contaminants of concern: 1,2-dichloroethene, tetrachloroethene, and trichloroethene. All three have been found in groundwater, surface water, soil, sediment, and solid waste. Trichloroethene was also targeted through an extraction well in a separate part of the site. These chemicals can harm human health through ingestion or skin contact with contaminated soil, soil vapors, or groundwater.

EPA traced the contamination to spills from a former chemical facility and a municipal landfill. Cleanup actions have included extraction wells to pull contaminated groundwater, air stripping to treat the extracted water, soil vapor extraction systems, a cover placed over the landfill waste area, and land and groundwater use restrictions. A 2024 modification to the remedy added municipal ordinances and institutional controls for added protection. Consent decrees signed in 1989 and 1991 guide who carries out the remedial work.

EPA completed a five-year review in March 2025. The review found that the cleanup systems and property restrictions largely protect the community. However, whether human exposure is fully under control cannot yet be determined, and there is not enough data to confirm that contaminated groundwater movement has been stabilized. Additional vapor intrusion sampling at the Marathon Electric facility will take about two years to complete before EPA can fully assess long-term protectiveness in that area. A Record of Decision Amendment is estimated between May and July 2028, and the next five-year review is scheduled for 2030. One business currently operates at the site, employing 309 people and generating about $60.2 million in annual sales.

Community members can get directly involved right now. In late February 2026, EPA sent letters to some residents and property owners asking for access to conduct vapor intrusion sampling. This sampling checks whether site contamination is affecting indoor air quality. Property owners who received a letter can sign a consent form online and send it to Mel Ross at GHD Environmental Consultant. Results will be shared directly with property owners, and if cleanup is needed, EPA will work with them to address it. Questions can go to Clara Copps, the EPA Remedial Project Manager, by email or phone.