Rare species of native Montana trout and other fish now have easier passage into the Clark Fork River thanks to an advanced fish ladder dedicated at PPL Montana’s Thompson Falls dam and hydro plant, PPL reported.
Thompson Falls Dam has a seven-unit hydroelectric plant. The units have a total generating capacity of 94 MW.
“Montana has healthy, diverse and dynamic river fisheries populations, and PPL Montana is doing its part, in collaboration with agency partners, to protect this valuable natural resource,” Pete Simonich, vice president and chief operating officer of PPL Montana, told guests who attended the dedication ceremony. “The Thompson Falls project is indicative of PPL Montana’s commitment to responsible power generation and river resource stewardship.”
Funded entirely by PPL Montana and built in collaboration with federal and state wildlife agencies and the Confederated Salish and Kootenai Tribes, the $7.5 million fish ladder reopens hundreds of miles of the upstream Clark Fork River and its tributaries for native bull trout, westslope cutthroat trout and other fish species. PPL Montana selected engineering firm GEI Consultants to provide ecological engineering services for construction of the fish ladder.
The new steel and concrete ladder system – which replaces an experimental, small-scale temporary fish ladder used since 2003 – has 48 step pools that will permit fish to gradually ascend about 75 feet to the top of, and over, the dam.
According to the U.S. Fish and Wildlife Service, it’s the first full-length fish ladder in the continental United States specifically designed to accommodate bull trout, a federally listed threatened species. It’s also the tallest fish passage facility of its kind in Montana.
Advanced biological monitoring, trapping and tagging technology and adaptive ladder operations will allow scientists to better support and enhance fish movement patterns and timing of runs in the Clark Fork River.
As part of the project, PPL Montana is improving public access and recreational facilities at Thompson Falls, including an observation deck for visitors to view fish ladder operations as well as pedestrian access to trails and other recreation sites on Island Park.
“PPL Montana deserves credit for not only funding the fish ladder but also with providing a visitor overlook of the facility, visitor information and educational opportunities for the local community,” said Mark Wilson, field supervisor with the U.S. Fish and Wildlife Service’s Division of Ecological Services in Helena. “The Thompson Falls project is a good example of state, federal, tribal and a private utility partnership to provide natural resource protection.”
The ladder’s design is targeted for bull trout, a federally listed threatened species, but all species will be able to use it. It’s the first facility of its kind in the continental United States designed for bull trout, which are a unique bottom-dwelling, reclusive species that tends to migrate mostly at night.
The project is part of PPL Montana’s federal operating license in compliance with the Endangered Species Act.
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