BOISE, Idaho -- The U.S. Army Corps of Engineers, Walla Walla District, in coordination with the Bureau of Reclamation, plans to begin gradually lowering the pool elevation of Lucky Peak Reservoir during the week of Aug. 10 as part of normal seasonal water management operations.
The Boise River reservoir system, which includes Anderson Ranch, Arrowrock and Lucky Peak reservoirs, is currently approximately 74% full and continues to provide water deliveries throughout the irrigation season. Due to this year's early snowmelt runoff, seasonal reservoir operations are occurring about one week earlier than typical.
Arrowrock Reservoir is forecast to reach its seasonal minimum pool during the second week of August. At that time, Lucky Peak Reservoir will begin its seasonal drawdown to continue supporting downstream water supply while creating flood risk management storage for the upcoming winter and spring runoff season.
Over the coming weeks, Lucky Peak Reservoir will be lowered to its winter pool elevation of approximately 2,945 feet. The reservoir is expected to decrease at a rate of approximately 2 feet per day, although the rate and timing may be adjusted based on irrigation demand, weather conditions and precipitation.
Because Lucky Peak's drawdown is managed through releases from Arrowrock Dam, releases from Lucky Peak Dam and flows in the Boise River are not expected to increase as a result of this operation.
As reservoir elevations decrease, visitors are encouraged to plan accordingly. Lower water levels will affect boat ramp accessibility and other recreational opportunities around the reservoir throughout the drawdown period.
Lucky Peak Reservoir is one of three reservoirs in the Boise River system that work together to provide flood risk management, irrigation storage, hydropower generation, recreation and environmental benefits throughout southwest Idaho.
The timing of the drawdown may be adjusted based on real-time weather conditions and irrigation demand. Additional operational updates will be provided as conditions warrant.