The Tomah Municipal Sanitary Landfill is an 18-acre unlined landfill in Monroe County, Wisconsin. The city operated it from 1959 to 1979. It was added to the Superfund National Priorities List in 1989 after operations contaminated groundwater with hazardous chemicals.
Eleven contaminants of concern have been identified, most found in groundwater. Volatile organic compounds include benzene, vinyl chloride, styrene, 1,2-dichloroethane, 1,2-dichloroethene, and 1,2-dichloropropane. Inorganic contaminants in groundwater are arsenic, cadmium, chromium, manganese, and thallium. Methane is also a concern tied to the landfill itself. Risks include human ingestion of or skin contact with contaminated groundwater.
Cleanup is organized into three operable units covering sitewide measures, landfill source control, and groundwater. A synthetic membrane cap with a clay layer and vegetated topsoil was built in 2000 to keep water out of the waste and slow contaminant movement. A gas extraction system safely vents landfill gases. Both systems have tested as functioning. For groundwater, the chosen approach is monitored natural attenuation, meaning natural processes reduce contamination over time, paired with institutional controls that restrict groundwater use in affected areas. In 2015, EPA updated those institutional controls through an Explanation of Significant Differences. Source text gives two different dates for when construction was completed, citing both 2001 and October 2003, so the precise completion date is unclear. The site reached readiness for anticipated reuse in 2014.
EPA has determined that human exposure is currently under control. Contaminated groundwater is stabilized in its original area with no unacceptable discharge to nearby Deer Creek. All cleanup goals for current and reasonably anticipated future land uses have been met, required land-use restrictions are in place, and no unacceptable risks from identified contaminants remain. EPA conducted its most recent five-year review in March 2025 and is currently working on the fifth such review. The site has not yet been deleted from the National Priorities List.
Community members with questions can contact EPA's Community Involvement Coordinator or Remedial Project Manager. Site records are also available for public review at the Tomah Public Library, 716 Superior Ave., Tomah, Wisconsin.
