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

It will also feature 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 have studied and tracked the fish below the dam for years, and determined the best site for a ladder is 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 will fund to bring the dam into compliance with the Endangered Species Act.

COP Construction of Billings will serve as general contractor.

Rock removal and excavation will begin this summer with construction started, with a target date for completion near the end of 2010.

The approximate cost of construction is $6M