A major installation project is underway at Montana’s Libby Dam to add flexibility to project operations and improve the dam’s overall electrical reliability.
The Generator Unit 6 installation project signals a milestone in the U.S. Army Corps of Engineers’, Seattle District’s continued efforts to enhance overall efficiency, reliability and performance of the dam’s hydropower-generating infrastructure.
The $34.8M installation project, which involves designing and constructing a new hydropower generating unit, along with all associated equipment to modernize its operation, was awarded May 29, 2024. Installation is expected to be completed April 2027.
“The new unit will allow us to maintain the five existing units more frequently, and ensure we remain a good steward of the environment and equipment entrusted to us,” said Ayden Capps, electrical engineer with Libby Dam.
In addition to the installation project, USACE is upgrading the selective withdrawal system at Libby Dam, to enable continued and enhanced ability to manage river temperatures downstream of the dam, which is critical for aquatic ecosystem, including resident trout species, threatened bull trout and endangered Kootenai River white sturgeon.
The U.S. Fish and Wildlife Service’s Biological Opinion for Kootenai River white sturgeon requires that five generating units be available for the annual sturgeon pulse. In addition to this requirement, having five units available during the spring reservoir refill period allows USACE to more consistently provide flood risk management in the Kootenai River valley downstream of Libby Dam.
“Libby Dam has provided flows for Kootenai River white sturgeon recovery in conjunction with flood risk management operations each spring since the 1990s,” said Libby Dam Fishery Biologist Greg Hoffman. “The addition of Unit 6 enables the Army Corps to continue to reliably provide ecosystem function flows and reservoir refill as we operate to provide flood risk reduction and hydropower production.”
Libby Dam spans the Kootenai River 17 miles upstream from the town of Libby in northwestern Montana.
USACE began construction of Libby Dam in 1966 and completed the structure in 1972, with the first commercial power coming on-line on August 29, 1975. By March 1976, three more units were put on-line, and the fifth unit was finished in 1984. The powerhouse was originally designed to accommodate eight generators.
On Aug. 23, 2025, USACE Seattle District will recognize Libby Dam’s 50 years of operations, providing flood risk management, hydropower, recreation, navigation and environmental stewardship, with a Memorial unveiling and Open House.
While megawatt-Hours (mwhs) generated by the dam vary by water year, in Fiscal Year 2019, the dam generated 161,51,000 mwhs, with an estimated market value of up to $57,322,000 (according to historical monthly market prices).
Public tours of the powerhouse will cease for summer 2025 and potentially throughout 2026, but there will be no power service interruptions to residents.