Milltown Reservoir Remediation and Dam Removal Program

Milltown dam, located on the Clark Fork River upstream of Missoula, Montana, was originally constructed in 1907 to provide hydropower-generated electricity for a sawmill. During the past century, metals-impacted sediment has washed down from historic mining and smelting operations in the Butte/Anaconda area filling Milltown dams reservoir and resulting in arsenic contamination of the local groundwater. In 2004, as part of remediation of the larger Clark Fork River Basin Superfund Site, the U.S. Environmental Protection Agency ordered the removal of Milltown dam and approximately 2.6 million cubic yards of reservoir sediment. Design and implementation of the Milltown reservoir and dam removal program has required orchestration of many factors involving numerous State, tribal and federal agencies, as well as community stakeholders. Project considerations have included environmental protection, dam safety, economic development, wetland mitigation, fish habitat/passage restoration, water supply well replacement, infrastructure impact mitigation and recreational enhancement, as governed by a host of statutes and regulatory agencies. This paper provides an overview of the issues associated with removal of the Milltown dam and how these issues were addressed as part of an integrated plan for removal of the dam and restoration of the Clark Fork River watershed. 18 pp., 1 table, 18 figures.