Monsanto Chemical Co Soda Springs Plant

⚠ Superfund · Construction complete

The site’s long-term remedy included monitored natural attenuation of contaminated groundwater and institutional controls. In 2018, EPA determined the remedy was no longer functioning as intended and additional work would be required to select new remedial actions.

Location

CitySoda Springs
CountyCaribou County
StateIdaho
Coordinates42.68703, -111.58780

Contaminants of concern

Contaminated media

Cleanup timeline

  1. Initial Assessment Completed — 01/09/1986
  2. Proposed to the National Priorities List — 05/05/1989
  3. Finalized on the National Priorities List — 08/30/1990
  4. Remedial Investigation Started — 03/19/1991
  5. Final Remedy Selected — 04/30/1997
  6. Final Remedial Action Started — 10/15/1998
  7. Construction Completed — 09/20/2000
  8. Deleted from National Priorities List — Not Yet Achieved
  9. Most Recent Five-Year Review — 08/28/2023
  10. Achieved Sitewide Ready for Anticipated Reuse — Not Yet Achieved

EPA references

Other Superfund sites in Caribou County

EPA-regulated facilities nearby

Understanding this Superfund site

Monsanto Chemical Co Soda Springs Plant is a federal Superfund site in Idaho. 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: Construction complete. Physical construction of the cleanup remedy is complete, though long-term monitoring and institutional controls typically continue for years or decades. Groundwater treatment systems, for example, often run long after surface cleanup finishes.

EPA has identified 10 contaminants of concern at this site, including arsenic, beryllium, cadmium. Contamination has been detected in other, soil, groundwater.

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.