The Coeur d’Alene River basin is one of the largest mining-related Superfund sites in the United States. It is not, however, unique. For example, just east of the Idaho-Montana border, the Clark Fork Operable Unit of the Milltown Reservoir-Clark Fork River Superfund site includes 120 river miles of the Clark Fork River contaminated with metals stemming from mining activities in upstream reaches (EPA 2004a). A 2004 report by the U.S. Environmental Protection Agency (EPA) Office of Inspector General (EPA 2004b) identified 63 hard rock mining sites (which do not include coal mining) listed on the National Priorities List (NPL), another 82 that were on Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS) but had not yet been listed on the NPL, and 11 potential CERCLIS/NPL sites.1 These represent only a small portion of all the abandoned hard rock mining sites in the United States. A Western Governors’ Association survey estimated that there were at least 400,000 abandoned or inactive hard rock mining sites in the West (WGA 1998a,b) and the Mineral Policy Center estimated in 1995 that, nationwide, there were 557,000 abandoned mines (Custer 2003). Although many of these are small sites presenting little or no human health risks, the EPA Inspector General found that the total cost of cleaning up the sites on the EPA inventory could be as much as $24 billion and that at least 19 of the sites already listed on the NPL are likely to have cleanup costs of $50 million or more (EPA 2004b).

By one formulation, these would be considered “megasites.”2 A Resources for the Future study has assessed the impact of such megasites on the budgetary state of Superfund (Probst et al. 2001), and a recent EPA advisory committee report (NACEPT 2004) discussed the issue of megasites and possible management options but provided no recommendations.

Mining megasites such as Coeur d’Alene typically involve multiple contaminants and contaminant sources and large volumes of waste material that have accumulated over many years of mining activity and are dispersed over wide areas. Large quantities of mining-related contaminants may have been deposited many miles from the original sources. Soils, sediments, surface water, and groundwater may be contaminated, and the hydrological relationships between these media may be complex and difficult to characterize.

The Superfund process has some serious difficulties in addressing this type of site. The following discussion focuses specifically on large mining


CERCLIS contains a list of all hazardous waste sites that are on the NPL or are being considered for the NPL. Many sites included in CERCLIS are unlikely ever to be listed on the NPL.


An EPA advisory committee characterized a Superfund site as a “megasite” if any combination of remedial action costs excluding long-term remedial actions exceeds $50 million (NACEPT 2004).

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