Falls dam upgrade under way

The Thompson Falls Dam is getting an upgrade this fall. NorthWestern Energy recently began a $5.6 million project to install two new radial spillway gates at the dam. The project got underway last month, and will continue through the winter.

Engineer BJ Cope visited the project last week, explaining that while the work to put in a temporary road began several weeks ago, the actual construction phase of the project just started recently. The project includes replacing four of the existing spillway gates with two radial gates. The advantage of the radial gates is that if river conditions change, NorthWestern can respond quicker. Instead of having to manually open gates, the radial gates open automatically.

IMCO General Construction from Spokane will have as many as 12 people working on the project through the winter, with project completion slated for spring, 2018 before high water hits. IMCO will also employ local companies as needed. A temporary road was put in below the dam to allow IMCO to move in equipment, including a crane, to work on the spillway gates. For that portion of the project, local subcontractors were hired. Thompson Falls Dam foreman Noel Jacobson said that using local resources was important in selecting a company for the job, and IMCO has done well in supporting the community.

The existing gates at the dam were installed in the 1980s. Cope said that this project is unique in that installing new gates on an old dam (the Thompson Falls Dam was completed in 1916) is not common. Design for the current project began in 2015. During that phase of the project, the design was changed so that NorthWestern Energy would not have to draw down the reservoir to complete the work. Jacobson said dam operations will continue as normal, and people using the reservoir should not notice any difference during the project.