RDU 2 – Lost Creek

Established in 1998, the Anaconda Regional Water, Waste & Soils (ARWWS) Operable Unit (OU) is the largest and most diverse Operable Unit in the Anaconda Smelter NPL site. As a result, the OU was separated into fifteen Remedial Design Units (RDUs) based upon factors such as location, source and type of contamination, and remedial needs. Click here for more information about the ARWWS OU.

RDU 2 – Lost Creek addresses approximately 300 square miles of soils and waters in southern Deer Lodge County impacted by smelter fallout from the smelting operations of the Anaconda Mining Company between 1884 and 1980. An accepted practice at the time, waste materials produced during the smelting process were disposed of in the area impacting nearly 6,000 acres within RDU 2. An estimated 13,000 acres of upland terrestrial soils located north of the city of Anaconda, in the vicinity of the rural neighborhood of Lost Creek, were also impacted by smelter fallout. Elevated levels of contaminates of concern (COCs) were found in surface and ground waters in the area. Sampling indicated roughly 28,000 acres of bedrock ground water and 4,800 acres of alluvial ground water were impacted.

RDU 2 – Lost Creek was separated into three design areas based on topography, hydrology, and treatment areas in order to better address the varying remedial needs. All three of these design areas are addressed by the Lost Creek Final Design Report and Remedial Action Work Plan (available in the Superfund Library). Remedial designs for RDU 2 included the installation of a permanent vegetative cover over contaminated soils to protect humans and wildlife from contact with COCs, while preventing the transport of COCs to adjacent lands or waters.

Visit the Superfund Library, located on the Arrowhead Foundation’s website, to review documents and research regarding the Anaconda Smelter NPL site. Additional information can also be found on the EPA’s website.