Modesto Ground Water Contamination

⚠ Superfund · Cleanup underway

Initial Actions

Location

CityModesto
CountyStanislaus County
StateCalifornia
Coordinates37.65910, -120.99640

Contaminants of concern

Contaminated media

Cleanup timeline

  1. Initial Assessment Completed — 06/01/1987
  2. Proposed to the National Priorities List — 06/24/1988
  3. Finalized on the National Priorities List — 03/31/1989
  4. Remedial Investigation Started — 03/21/1991
  5. Remedy Selected — 09/26/1997
  6. Final Remedy Selected — 08/20/2021
  7. Remedial Action Started — 09/22/1998
  8. Final Remedial Action Started — 06/13/2013
  9. Construction Completed — Not Yet Achieved
  10. Deleted from National Priorities List — Not Yet Achieved

EPA references

Other Superfund sites in Stanislaus County

EPA-regulated facilities nearby

Understanding this Superfund site

Modesto Ground Water Contamination is a federal Superfund site in California. The Superfund program, created by Congress in 1980, addresses sites where hazardous substances have been released or threaten release into the environment. EPA scores potential sites using the Hazard Ranking System; those that score high enough are placed on the National Priorities List.

Current status: Cleanup underway. Active cleanup is underway, meaning EPA has approved a remediation plan and work is in progress. Cleanup timelines vary widely — some sites take decades depending on contamination depth, groundwater involvement, and funding availability.

Contaminants of concern include tetrachloroethene, toluene, trichloroethene. Contamination has been detected in air, groundwater, soil gas, soil.

If you live near this site and have health concerns, your state health department can provide site-specific guidance. EPA maintains a community involvement program for most NPL sites, and site documents — including the Record of Decision, five-year reviews, and public health assessments — are typically available through EPA's Superfund site profile.