"Removing a Dam, Restoring a River: The Story of Milltown, Montana"

Located at the confluence of the Clark Fork and Blackfoot Rivers in western Montana, the Milltown Dam blocked fish passage and collected mine waste from upstream mining activities for a century.  The sediments deposited behind the Milltown Dam contained arsenic, contaminating the local drinking water aquifer and posing a risk to public health.  The sediments also contained copper and would scour from the Reservoir, resulting in chronic, and sometimes acute, impacts to the downstream fishery.

In 2004, the US Environmental Protection Agency and the Montana Department of Environmental Quality issued a Record of Decision for the Milltown Reservoir Sediments Superfund Site (part of the 120-mile long Milltown Reservoir/Clark Fork River Superfund Site).  The cleanup plan called for removal of the Milltown Dam and approximately 2.2 million cubic yards of contaminated sediments.  

Bull trout are native to this area and are listed as threatened under the Endangered Species Act.  Removal of the fish passage barrier (dam) and habitat for northern pike (reservoir) assist with bull trout recovery. 

This project integrates Remediation, Restoration, and Redevelopment – the “3Rs”.   The goals of this project are to restore the local drinking water aquifer, provide fish passage, restore the local fishery, and return the Clark Fork and Blackfoot Rivers to their naturally-functioning, free-flowing state.  

Today, Remediation and Restoration are in their final phases and the emphasis is shifting to Redevelopment – transforming a Superfund Site into a new State Park. 

This presentation provides insights regarding:

• Integration of Remediation, Restoration, and Redevelopment;
• Description of the Best Management Practices to minimize impacts during dam and sediment removal;
• Monitoring of the fishery, aquatic life, groundwater, and surface water quality to manage risks and measure progress; and
• Successful collaboration with private and public partners at the tribal, federal, state, and local levels