We revisited Thompson Falls this spring. The town is situated in northwestern Montana on the Clark Fork River, at a site of a natural waterfall. There have been two dams built at the site — one across the main channel of the river (which contains extensive spillways and a fish ladder). A second dam connects to a hydroelectric generating station and is not featured in this post.
The photos in this blog are of the Main Channel Dam which is approximately 54 feet (16 m) high and 1,016 feet long. It has a long overflow spillway section which was actively allowing excess water from the spring melt and rains bypass the hydroelectric dam.
The following video gives you an idea of the power of the water:
The dam was built more than 100 years ago, and the first power from it was generated in 1915. The site and adjacent buildings form the Thompson Falls Hydroelectric Dam Historic District, listed on the National Register of Historic Places.
A full-height fish ladder was completed around 2010 on the main dam. The ladder has helped pass thousands of fish of multiple species upstream including endangered species like bull trout, westslope cutthroat trout, and others. Downstream passage occurs over the dam or through the powerhouse.
The photo below is looking downriver from the dam, the water remaining quite turbulent.
