LIBBY, Montana -- U.S. Army Corps of Engineers (USACE), Seattle District, Water Management officials indicate that 2025 is shaping up to be one of the driest years on record for Lake Koocanusa, with extremely low precipitation and a mostly depleted snowpack.
Although Libby Dam has released minimum discharge since January 2025, following USACE’s flood risk management operations, the little remaining snowpack and forecasted inflows will likely result in a peak reservoir elevation this summer less than previously projected.
The current Northwest River Forecast Center (NOAA) April through August 2025 runoff forecast for the Kootenai Basin above Libby Dam (Libby, Montana) is the third lowest in 74 years.
The Army Corps’ official Water Supply Forecast (WSF) at Libby Dam dropped from 4,944 kaf to 4,670 kaf between May 1 and June 1. Monthly WSFs are available at: https://www.nwd-wc.usace.army.mil/report/libf/
USACE officials indicate current modeling shows Lake Koocanusa will likely be drafted slightly below the 2,446.7-foot elevation target for end of September, and peak water elevation may be about 6 feet below the normal refill target of 2,454 feet, potentially impacting recreation in Lake Koocanusa (beaches and boat docks).
The final Army Corps’ May WSF determines the volume of water released for Kootenai River white sturgeon, the minimum discharge for bull trout downstream of Libby Dam during the summer months, and the target Lake Koocanusa elevation at the end of September.
Despite the projected refill scenario, USACE has met and will meet all U.S. Fish and Wildlife Service and National Marine Fisheries Columbia River System Biological Assessment and Biological Opinion requirements:
- Minimum sturgeon volume of 0.8 MAF for Tier 2 Water Year,
- Bull trout minimum flow (7 kcfs through August and 6 kcfs through September); and
- End-of-September maximum target Lake Koocanusa elevation of 2,446.7 ft. for juvenile salmon and steelhead flow augmentation in the Columbia River.
As the Water Year progresses, USACE officials will continue to coordinate, as needed, with the Services and regional managers, including the Columbia River Basin Technical Management Team.
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