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Eagle Mine

This site is one of the "Superfund" hazardous waste sites in Colorado. A site qualifies for the National Priorities List (NPL or Superfund list) when the U.S. Environmental Protection Agency (EPA) determines there is a release or threatened release of hazardous substances that may endanger public health, welfare or the environment. In Colorado, the lead agency for Superfund remediation may be either the EPA or the Colorado Department of Public Health and Environment (the state health department).


Site Map




The Eagle Mine site consists of the Eagle Mine and associated mining wastes between Gilman and Minturn in Eagle County, Colorado.  The mine is located approximately eight miles southwest of Vail and one hundred miles west of Denver.  The 235-acre site includes the Eagle Mine workings, the town of Gilman, eight former mine tailings piles, Rock Creek Canyon below Highway 24 and at least 14 waste rock piles.  The Eagle River flows northwesterly through the site and past the town of Minturn (population 1,514).  The consolidated tailings pile is 1,500 feet southeast of the Minturn Middle School and numerous residences.




Mining first began in the Gilman area in the late 1870s with the discovery of gold and silver deposits.  By the mid-1890s, production from these mines declined, but picked up in 1905 with the mining of lead and zinc deposits.  Four roasting and magnetic separation plants, used to process the ore, were constructed and the roaster process continued until 1919.  An underground mill, constructed to extract lead and zinc metals, operated fomr 1919 to 1979.  Copper-silver production continued until 1984 when the mine workings were allowed to flood.   The State of Colorado filed notice and claim against the former mine ownners for natural resource damages under the Superfund law in 1985.  The site was placed on the list of Superfund sites in June 1986.


The major contaminants of concern are heavy metals such as lead, zinc, cadmium, arsenic and manganese associated with the mining wastes.  The major pathways of concern are surface water contamination to the Eagle River, alluvial groundwater contamination and ingestion/inhaltion of mining wastes.


The State of Colorado and the previous mine owner/operator (Gulf + Western Industries, now Viacom International, Inc.) entered into a consent decree and Remedial Action Plan to conduct remedial actions in June 1988.  The cleanup plan included flooding the mine workings by bulkheading mine adits, relocating all processed mine wastes and contaminated soils to one main onsite tailings pile, capping this pile with a multi-layer clean soil cap and revegetating all disturbed area with native plant species.


The relocation of mine wastes began in 1988 and was generally completed in 1994. Capping of the main tailings pile was essentially completed in 1997.  Reclamation of the tailings removal areas and completed cap sections have resulted in initial vegetation establishment.  Flooding of the mine workings resulted in unacceptable seepage into the Eagle River beginning in late 1989.  A water treatment plan was constructed in 1990 to collect mine seepage, groundwater at the main tailings pile and precipitation accumulation on tailings removal and relocation areas.  The water treatment plant treats approximately 140 million gallons of water annually, and removes approximately 175 pounds per day of zinc.  Water quality in the Eagle River has shown improvements beginning in 1991 and should continue as the remedial actions are completed.


EPA initiated additional studies of the site in 1992 and issued a Record of Decision (ROD) in 1993 that identified additional site investigation and remedial actions to be implemented at the site.  EPA, the State of Colorado and Viacom entered into a three-party Consent Decree and Statement of Work in August 1995 to implement the Record of Decision.  This agreement also included a program to sample water quality, aquatic insects and fish populations in the Eagle River to assess the effects of the remedial actions and to evaluate the possibility of establishing biological-based cleanup standards for the site.  The biological monitoring is on-going.


In addition, more than 700 cubic yards of zinc concentrates have been removed from the Dryer House and taken to the consolidated tailings pile.  Viacom is attempting to intercept and divert 100-200 gallons per minute of clean groundwater from the Eagle Mine. 


The first 5-Year Review for the site was completed in October 2000.  The review concluded that public health risks have been removed and that significant progress has been made in restoring the Eagle River.  The graph below illustrates the downward trend in zinc concentrations (red line) in the Eagle River and the corresponding marked increase in the brown trout population (blue line).


Graph of zinc concentrations versus brown trout population

In October 2001, EPA declared construction of the required elements of the remedy completed, and the site is now in the Operations and Maintenance phase.  As a result of the remedial actions, significant improvement in water quality in the affected segments of the Eagle River has occurred.  A site-specific biological study has also been conducted to define a "healthy biological condition" for the aquatic community, which incldes a set of biological measures for brown trout and macroinvertebrates.



In addition to the on-going remedial activities at the Eagle Mine Site, a developer has purchased portions of the site and is investigating redevelopment of the site into a private golf and ski resort.



Wendy Naugle, State Project Manager



Warren Smith, State Community Involvement Coordinator


1-888-569-1831 ext 3373 toll-free outside the 303/720 area code


Leslie Sims, EPA Remedial Project Manager