Project Summary

Northwestern Energy contracted IMCO to install two new 41-foot wide radial gates on the main dam spillway of Thompson Falls Dam. The two new radial gates replace the existing flashboard system and will provide Northwestern Energy with additional automated spill capacity. The radial gates must be installed while keeping the upstream reservoir level full of water. Work scopes include constructing access to the spillway, protecting the work area from water, concrete demolition, new concrete placement, structural steel, gate installation, and automated hoist installation.



Sanders County, Montana


Northwestern Energy

Contract Amount



Morrison Maierle

Anticipated Completion

April 2018