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Planning and implementation of a comprehensive ecological risk assessment at the Milltown Reservoir-Clark Fork River Superfund Site, Montana

Journal Article · · Environmental Toxicology and Chemistry; (United States)
 [1];  [2]
  1. Environmental Toxicology International Inc., Seattle, WA (United States)
  2. Environmental Protection Agency, Helena, MT (United States)

The US Environmental Protection Agency (EPA) initiated an innovative ecological risk assessment program at the Milltown Reservoir-Clark Fork River Sediments Superfund Site in 1989. The site is located in the Clark Fork River (CFR) basin of western Montana, and consists of 160 km (100 miles) of the CFR and an 820-acre wetland at Milltown Reservoir. The focus of the assessment was to identify chronic risks to ecological receptors from metals-contaminated sediments that have deposited in aquatic and terrestrial habitats of the site. Lack of established sediment or soil quality criteria, the extent of habitats within the watershed, and anticipated complex sediment and soil chemistry led to a unique laboratory and field-based approach for the baseline risk assessment. Study tasks evaluated aquatic, wetland, and terrestrial habitats across multiple trophic levels. The risk assessment integrated the results of these studies as a triad of chemical, toxicological, and ecological information. The comprehensive nature of the risk assessment was designed to help determine a remedial action for the wetland operable unit and set the basis for additional studies in the upper Clark Fork River watershed. As the problem formulation step in the EPA's risk assessment methodology, this article describes the background of the site, the approach and conceptual model for the risk assessment, and the planning process for implementing the various field and laboratory studies.

OSTI ID:
6792755
Journal Information:
Environmental Toxicology and Chemistry; (United States), Journal Name: Environmental Toxicology and Chemistry; (United States) Vol. 13:12; ISSN ETOCDK; ISSN 0730-7268
Country of Publication:
United States
Language:
English