Silver mining at the Standard Mine ran from 1874 to 1974 and left behind heavy metal contamination in soil, surface water, and groundwater in Colorado's Gunnison National Forest. The site was added to the EPA's National Priorities List in September 2005 and has been in active cleanup since 2006. It sits within the Ruby Mining District, and contamination has flowed into Elk Creek and downstream toward Coal Creek and other water users.
The four contaminants of concern are cadmium, lead, and zinc in surface water, and manganese in solid waste. The main environmental risks fall on aquatic plants and animals in Elk Creek, where cadmium, lead, and zinc levels exceed Colorado water quality standards and may limit the presence and growth of aquatic life. Human health risks from contaminated soils near the mine workings were found acceptable after source control removal work finished, and human exposure is currently under control.
Cleanup work has unfolded in phases. A sitewide removal action ran from 2006 to 2008. After a remedial investigation, feasibility study, and a final remedy selection in September 2011, construction began in September 2014. Phase 1 finished in 2017 and included a concrete flow-through bulkhead, controls on adit discharge, waste rock stabilization, and revegetation. In June 2023, EPA closed the bulkhead and modified the cleanup plan to test long-term effectiveness. Operation and maintenance responsibilities shifted to Colorado in November 2018. The most recent five-year review, completed in May 2025, found the cleanup is protective of human health and the environment with no exposure to contaminated soil or waste. However, groundwater migration is not yet under control, physical construction is not complete, and the site has not been deleted from the National Priorities List. Phase 2, which would add a passive water treatment system to further improve Elk Creek water quality, will be decided after a monitoring period ends in 2027.
Community members can attend annual public meetings hosted by EPA and partner agencies. Meeting announcements are posted on the EPA's site profile. Site documents, including the 2025 five-year review and a related fact sheet, are available on the EPA's site profile, at the Crested Butte Old Rock Library, and at the EPA Records Center in Denver by calling (303) 312-7273 or (800) 227-8917 extension 312-7273.
