Cabinet project to aid bull trout

Avista has initiated the construction of the Cabinet Gorge Dam Fishway (CGDF), expected to be complete in the fall of 2021. This is part of Avista’s compliance with its federal operating license and the Endangered Species Act to provide safe and effective passage of the threatened bull trout traveling from Lake Pend Oreille to their spawning tributaries in Montana.

Construction of the CGDF is the result of more than 20 years of research and testing to determine how best to move migrating bull trout over the 208-foot-tall Cabinet Gorge Dam, according to Avista. The design and construction of the CGDF is in collaboration with the Clark Fork Settlement Agreement Management Committee, which consists of 27 groups that include U.S. Fish and Wildlife Service, U.S. Forest Service, Idaho, Montana, 5 Native American Tribes, Sanders County, and numerous non-governmental organizations. Once built, this will fulfill the upstream passage requirements for Cabinet Gorge Dam identified in the Clark Fork Settlement Agreement.

The CGDF is designed to capture adult bull trout and westslope cutthroat trout migrating upstream from Lake Pend Oreille to their spawning tributaries in Montana. Once captured, these fish will be moved to a holding and handling facility where data will be collected prior to trucking and releasing them to their tributary of origin to spawn. Non-targeted fish will be returned to the river.

With construction, Avista noted that periodically, little or no water will flow from Cabinet Gorge Dam to facilitate this construction. As a result, river flows between Cabinet Gorge Dam and Lake Pend Oreille will be low and may change rapidly and without warning. River users are advised to use extreme caution during construction. Avista will post warning signs notifying river users when flows will be low and unpredictable.

Construction of the CGDF will involve three phases of work.

Phase 1, July-December 2019: Construction of a cofferdam surrounding the area around the fishway location. Flows in the river below Cabinet Dam will be kept lower during daylight hours to allow access to the site to install the cofferdam.

Phase 2, January 2020-March 2021: construction of the concrete fishway trap will take place inside the cofferdam area. Flows in the river below Cabinet Dam should remain within normal operating protocols.

Phase 3, March 2021– October 2021: Finishing touches on the fishway, cofferdam removal, water system and crane installation. Flows in the river below Cabinet Dam should remain within normal operating protocols.

Slayden Construction, General Contractor and Stantec Consulting, Engineer of Record, have been actively engaged and working on this project. Local contractors working on the project include Wood’s Crushing and Hauling, Ginno Construction Company, as well as Interstate Concrete and Asphalt.

Public viewing of the construction activities can be observed from the Cabinet Gorge Dam Viewpoint off of Highway 200 at the Montana-Idaho border.