PPL Montana has received approval from the Federal Energy Regulatory Commission and U.S. Fish and Wildlife Service to begin construction of a permanent fish ladder at its hydroelectric dam at Thompson Falls, giving two rare species of trout safe passage into their native spawning waters.
Preconstruction work will begin shortly on the project that will reopen hundreds of miles of the upstream Clark Fork River and its tributaries for bull trout, westslope cutthroat trout and other fish species.
This multimillion-dollar project will create dozens of jobs in Montana during construction. The project is part of PPL Montana’s federal operating license, its commitment to fisheries and river resources, and compliance with the Endangered Species Act. The project will be funded entirely by PPL Montana.
COP Construction of Billings, with expertise in hydroelectric plants, will be the general contractor. Work will begin in the summer, starting with rock removal and excavation. No blasting will be needed. Construction of the fish ladder is expected to start at the end of the year and will be completed by the end of 2010.
“This innovative design will attract selected fish species with water cascading down the ladder at specific speeds, causing them to move toward and into the fish passage system,” said Jon Jourdonnais, PPL Montana’s director of hydro licensing and compliance. “We’re particularly targeting bull trout, which is a federally listed threatened species, and westslope cutthroat trout, a species of special concern.”
In order to decide how best to design the fish lift, PPL Montana biologists, along with state, federal and Confederated Salish and Kootenai tribe fisheries biologists, have studied and tracked the fish below the dam for years.
Based on the studies, the fish ladder will be placed at the north side of the main dam channel, where the migrating bull trout and other fish have been shown to seek upstream passage.
“Bull trout and other fish will instinctively climb the ladder step pools in this specifically designed Thompson Falls ladder in a manner similar to other fish ladders in the Northwest,” Jourdonnais said.
The fish ladder — which will replace an experimental, small-scale temporary fish passage system used since 2003 — will have 47 individual concrete step pools, each filled with water, that will permit fish to gradually ascend about 75 feet to the top of and over the dam, he said.
There will be a mechanical lift and sorting tank that can be used as part of the ladder operation, where biologists can radio tag, examine or selectively transport the fish by truck. An area for the public to view ladder operations also is being evaluated.
Thompson Falls is one of two PPL Montana dams west of the Continental Divide — the other being Kerr Dam on the Flathead River, which empties into the Clark Fork. The Clark Fork River empties into the Columbia River, which in turn empties into the Pacific Ocean.
PPL Montana provides safe, reliable energy from coal-fired power plants at Colstrip and Billings, as well as 11 hydroelectric plants along West Rosebud Creek and the Missouri, Madison, Clark Fork and Flathead rivers. It has a combined generating capacity of more than 1,200 megawatts and has offices in Billings, Butte and Helena. PPL Montana and its 500 employees are dedicated to Montana and its communities, supporting educational, environmental and economic development programs across the state. PPL EnergyPlus operates a trading floor in Butte that markets and sells power for PPL Montana in wholesale and retail energy markets throughout the western United States. PPL Montana and PPL EnergyPlus are subsidiaries of PPL Corporation (NYSE: PPL).