The Clark Fork complex includes four sites heavily affected by mine waste and encompasses the cities of Butte and Anaconda, Mont. and nearly 120 miles of river corridor downstream of Butte. Abt Global’s staff served as the prime contractor for this study, providing case management, injury assessment, economic damages, restoration planning, and litigation support to the state of Montana.

Abt staff prepared environmental site assessment documents, served as lead testifying experts for the case in U.S. federal court. Our work included detailed scientific investigations of the fate and transport of metals, and effects of historical mining on the aquatic and riparian resources of Silver Bow Creek and the Upper Clark Fork River, on groundwater resources in and around Butte, and on terrestrial resources around the smelters in Anaconda.

We conducted toxicological investigations of behavioral avoidance responses of rainbow and brown trout, dietary effects evaluations, and evaluations of the effects of pulsed metals exposures and metals acclimation on trout. Our scientists also conducted an extensive laboratory investigation to evaluate toxicological effects of metal-contaminated sediments from the Clark Fork River Basin on rainbow trout. The state used the results of these studies to assess a range of injuries to trout caused by metals in the basin.