Bonner Dam completion initiates bridge replacements and sediment cleanup in Missoula County

The government meeting held on May 2, 2025, focused on significant developments regarding the Bonner Dam and its surrounding infrastructure in Missoula County. The discussions highlighted the historical importance of the Bonner Dam, completed in January 2008, which played a crucial role in generating electricity for local industries, particularly the mill that supplied materials for mining operations in Butte.

The meeting addressed the ongoing cleanup efforts related to arsenic contamination from the mining activities, which have been in progress for over two decades. Officials expressed satisfaction with the progress made in this area, emphasizing the importance of environmental remediation.

A key topic was the replacement of several bridges in the Bonner area, including the Highway Bridge and the Black Bridge, which are being updated due to safety concerns and to reduce the number of piers in the river. The Black Bridge, previously used as a highway bridge, will be preserved for pedestrian use, thanks to community input and engineering solutions that allow it to be transformed into a single-span structure.

The meeting also covered the sediment removal project currently underway in the river, which aims to address the contamination caused by copper and magnesium from historical mining operations. The sediments are being transported to a repository established by the Anaconda Company, with plans to cap the area to prevent dust storms and promote vegetation growth.

Looking ahead, officials announced that the powerhouse associated with the dam will be removed in the coming months, with the hybrid pedestrian bridge expected to be completed by the start of the school year. The Highway 200 Bridge is projected to follow shortly after, and the spillway removal is scheduled for approximately one year from now, contingent on river levels.

Overall, the meeting underscored the community's commitment to preserving historical structures while addressing environmental concerns and enhancing public safety through infrastructure improvements.