EPA Superfund Site
BLACK BUTTE MINE
OR | EPA ID OR0000515759
About this site’s exposure pathways: As of June 2025, the Black Butte Mine Superfund site is considered “Current Human Exposure Not Under Control” (HENC). The main pathway of concern is mine-contaminated soil or sediment from the site entering surface waters and settling downstream, causing mercury biomagnification in the food chain and resulting in fish with mercury levels that exceed safe consumption criteria. The site is divided into three sections, known as Operable Units (OU). These include the mine area (OU1), the Coast Fork Willamette River below the mine and above the reservior (OU2), and the Cottage Grove Reservoir (OU3). The EPA is currently in the Remedial Investigation (RI) and Feasibility Study (FS) phase for all OUs. The Human Health Risk Assessments found unacceptable risk for potential future residents at the mine site OU1 due to total mercury in soils, and for recreational anglers due to methylmercury in fish tissue within the two downstream areas (OU2 & OU3). The EPA will develop options for cleanup as necessary during the FS process. A non-time critical removal action at Operable Unit 1 (mine site) was completed in 2018-2019 to reduce immediate risks from mine site source areas for mercury to the downstream system. A combined OU1/OU2 interim ROD is currently planned for 3/2027 to address source control, followed by an OU3 interim ROD in 3/2028. Addressing past and ongoing continuing releases that contribute to high levels of mercury in fish tissue in the reservoir may take many years to achieve reductions. Mercury is also a global atmospheric pollutant that can cause issues in fish tissue concentrations absent of a mine source. The State of Oregon Health Authority (OHA) issued a "green" fish advisory for the reservoir in 2012 and is currently working with the EPA, Oregon Dept of Fish and Wildlife, and US Army Corps of Engineers (USACE) to increase risk communication via updated signage and public outreach. If you are impacted by risks inherent at this site, follow the OHA Fish Consumption Advisory to limit exposure. The EPA currently anticipates that human exposure will be under control by 2043 because long term monitoring from planned Remedial Action work at the site will be completed at that time. Community notice regarding OHA Fish Consumption Advisory limits are posted at the Cottage Grove Reservoir access points by the USACE, in coordination with OHA and the EPA.