Leadville, located in the mountains of Colorado approximately 100 miles west of Denver, was historically a rich mining district. Silver, gold, copper, zinc, manganese, and lead were all mined in the area beginning in the mid-1800s, but mining has since subsided as the main economic driver for the district. Because of environmental contamination from mining activities, the area known as the California Gulch Superfund site was placed on the U.S. Environmental Protection Agency’s (EPA’s) National Priorities List in September 1983. The site covers approximately 18 square miles in and around Leadville, Colorado, and contains thousands of piles of mine waste and drainage sites that discharge into the California Gulch from underground abandoned mines. The EPA began emergency remediation at the site in 1986 and remediation continues to this day. In 2006, on behalf of the public, the Natural Resource Trustees (Trustees), which include U.S. Department of the Interior agencies and the State of Colorado, estimated damages to natural resources at the California Gulch Superfund site. The Trustees determined that the release of hazardous substances from the site, including heavy metals and acid, have resulted in injuries to groundwater and aquatic and terrestrial resources. Injured terrestrial resources include upland areas associated with mine waste deposits and floodplain areas with contaminated riparian zones, irrigated meadows, and fluvial deposits. Surface water in California Gulch has been observed to exceed the adverse effects thresholds for aquatic biota for zinc, cadmium, and other metals, and these high metal concentrations have resulted in nearly a complete loss of some biological communities (Stratus Consulting Inc., 2010).
A 2008 Natural Resource Damage Assessment settlement agreement requires the Resurrection Mining Company and Newmont USA Limited to pay $10.5 million in damages for injured natural resources resulting from the discharge of hazardous substances from the California Gulch Superfund site. Additionally, the 2009 ASARCO LLC bankruptcy resulted in a $10 million, plus interest, settlement to the Trustees. These settlement funds were used for many restoration projects in and around Leadville, Colorado, including the Arkansas Instream Habitat Restoration Project, the Canterbury Tunnel Project, and the Dinero Tunnel Project. A great deal of progress has been made as a result of these and other restoration projects in the area and, as of 2014, 70 percent of the site had been delisted from the EPA’s National Priority List. The U.S. Geological Survey collected data on restoration activities and expenditures to estimate the economic activity supported by these restoration projects.
Background information on the Arkansas River instream habitat restoration was obtained from Laura Archuleta, U.S. Fish and Wildlife Service, written commun., 2015; and from California Gulch Superfund site Natural Resource Damage Assessment and Restoration case documents at
Stratus Consulting Inc., 2010, Restoration plan and environmental assessment for the Upper Arkansas River Watershed: Stratus Consulting Inc., 111 p., accessed June 1, 2015, at http://www.cerc.usgs.gov/orda_docs/DocHandler.ashx?ID=152.