EPA completed a remedial investigation of contaminated surface material in January 2012 and completed a feasibility study in January 2013 to evaluate surface cleanup alternatives. A Record of Decision was signed on April 18, 2016 and on October 23, 2020 the 100% Remedial Design was completed for Operable Unit 1.
| City | Riddle |
|---|---|
| County | Douglas County |
| State | Oregon |
| Coordinates | 42.85447, -123.38261 |
Formosa Mine is a federal Superfund site in Oregon. 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.
EPA has identified 4 contaminants of concern at this site, including arsenic, cadmium, copper. Contamination has been detected in solid waste.
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.