|The Formosa Mine Superfund Site is located on Silver Butte, about 10 miles south of the town of Riddle, in Douglas County, Oregon. The site was added to the National Priorities List (NPL) in 2007. The acid rock drainage flowing from the mine and mine materials have severely degraded 13 miles of Middle Creek and the South Fork of Middle Creek, affecting macroinvertebrates, resident fish, coastal steelhead trout, and Oregon coastal Coho salmon. |
The Proposed Plan for Operable Unit 1 (OU1) (PDF) (32 pp, 2.8MB) of the site was released on January 6, 2015. Operable Unit 1 includes surface and subsurface mine materials. In a separate evaluation, EPA will develop a Proposed Plan for Operable Unit 2 (OU2), which includes groundwater, surface water and mine materials within the underground mine workings. EPA is reviewing comments submitted on the Proposed Plan and preparing the Record of Decision for Operable Unit 1.