Construction Details

The fish ladder flow design is flexible from 6 cfs pool to pool flow and with auxiliary water flow attraction flow totaling up to 80 cfs.

The ladder is designed to particularly targeting bull trout, which is a federally listed threatened species, and westslope cutthroat trout, a species of special concern. The fish will climb over 50’ from the river to the reservoir.

The ladder has 47 individual concrete step pools, each filled with water, that will allow the fish to gradually ascend to the reservoir through the dam.

It also features a mechanical lift and sorting tank where biologists can install radio tags in fish, examine them and select fish they want to transport by truck.

Biologists studied and tracked the fish below the dam for years, and determined the best site for a ladder was at the north end, where migrating bull trout and other fish have been shown to seek upstream passage.

The Federal Energy Regulatory Commission and U.S. Fish and Wildlife Service approved the project, which PPL Montana funded to bring the dam into compliance with the Endangered Species Act.

COP Construction of Billings served as general contractor.

The approximate cost of the project was $7.5 million.