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U.S. v. Apache Energy & Minerals Co. (Cal Gulch) (D. Colo.)
Photograph showing the fluvial tailings deposit along the upper Arkansas River south of Leadville, Colorado. Courtesy of USGS.
California Gulch drainage flowing into the upper Arkansas River (Pre-Remediation).  Photo Courtesy EPA.Several settlements were negotiated by Environmental Enforcement Section (EES) attorneys in which contamination at the California Gulch Superfund Site in Leadville, Colorado was addressed – a case filed under Sections 106 and 107 of CERCLA, styled as U.S. v. Apache Energy and Minerals Company, et al. and in a large bankruptcy proceeding In Re Asarco, LLC.

The site, deriving its name from the historic California Gulch mining district where mining of gold, silver, lead, and zinc began in 1857, is located 100 miles west of Denver in the heart of the Rocky Mountains and at the headwaters of the Arkansas River. Covering 16.5 square miles, the site encompasses the city of Leadville, Colorado (elev. 10,350’). A century of mining, milling, and smelting left lead, zinc, and other heavy metal contamination throughout the mining district which impacted down-stream areas where Spring snow melt, flooding, and irrigation carried eroding mine wastes and contaminated sediments as well as the flow of acid mine and acid rock drainage.

An innovative 1994 consent decree:

    Equitably divided the complex site into “areas of responsibility” among the primarily liable parties; and

    Provided for a unique “total lead” abatement program that addressed all sources of lead exposure to children including contaminated soil as well as leaded paint and leaded pipes in Victorian era homes.


    The settlements led to over $200 million of remedial work being completed or paid for by mining companies that contributed to the heavy metal contamination at the site.

    In addition, the long-term management and treatment of the acid mine drainage from the so-called Yak Tunnel has been secured, the health of Leadville children is being protected through a continuing community-based health program, and $20 million of restoration projects targeted at improving the fishery and avian habitat in the upper Arkansas River are being jointly implemented by federal and state natural resource trustees.

California Gulch below Apache Tailings Impoundment (both Post-Remediation).  Photo courtesy EPA.Note: The Yak Tunnel is a 4-mile long tunnel bearing into the mountain side and draining an estimated 46 – 52 million cubic feet of interconnected underground mine workings into the California Gulch drainage. Uncontrolled surges of heavy metal sediments from the Yak Tunnel led EPA to place the site on the National Priorities List in 1983. A surge lasting 24 hours in 1985 released an estimated 1 million gallons of acid mine drainage and contaminated sediments turning the Arkansas River orange for many miles.

The Yak Tunnel became the first of 12 “operable units” of environmental remediation activities at the site. Click on the film icon that follows to see a brief video clip about one of the Yak Tunnel’s “blowouts.” Some historical as well as pre- and post-remediation photographs also follow. The photographs showcase the effort made by federal and state agencies, mining companies, local officials, nonprofit groups, and local citizens to coordinate environmental cleanup activities with the preservation of the site’s historic resources. The 12-mile Mineral Belt Bike Path, a unique trail that loops through many of the site’s historic mine tailings and mining artifacts, has been designated a national historic trail.


Last Updated: September 2014