Located two miles east of Anaconda, early risk assessments discovered that the community of Mill Creek was severely impacted by contamination from the smelting operations in Anaconda. Elevated urinary arsenic levels were found in the young children of Mill Creek. In 1986, the young children of the Mill Creek community were temporarily relocated. Further testing determined that the area was unsafe for residential living due to current contamination and potential sources of recontamination remaining within the Anaconda Smelter NPL site. In autumn of 1988, the 37 residents of Mill Creek were permanently relocated.
Final remedial action within the Mill Creek Operable Unit (OU), spanning approximately 100 acres, was completed in 1999. Remediation included home demolition, debris removal, soil clean up, grading, and re-vegetation. Thereafter, the area was zoned for commercial/industrial use and remedial designs to ensure human, wildlife, and environment safety such as fencing and signage were initiated.
As remediation within the Anaconda Smelter NPL site progressed, the Mill Creek OU was incorporated into the Old Works/East Anaconda Development Area (OW/EAD) Operable Unit (OU) as a subarea known as the Mill Creek Addition. The OW/EADA Record of Decision (ROD) provided for the cleanup of soils in the Mill Creek Addition exceeding 1000 ppm (parts-per-million) arsenic using protective covers. Ground and surface water issues within the Mill Creek OU were deferred to the standards established in the Anaconda Regional Waste, Water and Soils (ARWW&S) Operable Unit (OU) Record of Decision (ROD).
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.