Reclamation refills Truckee reservoirs early to improve water operations

CARSON CITY, Nev. - The U.S. Army Corps of Engineers South Pacific Division has approved a Bureau of Reclamation request to temporarily modify operations at Prosser Creek, Stampede, and Boca dams. The change, authorized through a planned major deviation from the 1985 Truckee Basin Water Control Manual, allowed reservoir refilling to begin in mid-March, more than a month earlier than typically permitted.

The earlier refill enables capture of additional spring runoff without increasing flood risk under current conditions. As a result, reservoirs are more likely to fill completely or reach higher levels than under standard operations. At Stampede Reservoir, the deviation also increases the likelihood of maintaining higher water levels for longer periods, supporting greater hydropower production through increased flows at the powerplant.

The 40-year-old Water Control Manual that guides flood control operations in the Truckee Basin prohibits reservoir refill in the spring until snowpack declines to specified levels. In some years, this prevents reservoirs from reaching full capacity, even during above-average water conditions. The manual also requires reservoirs to be drawn down in the fall to maintain flood storage space through winter, limiting the ability to carry over water from wet periods into drier years.

This deviation stems from a Reclamation cost-share study evaluating these operational constraints. The study identified opportunities to improve basin management, including updating reservoir guide curves and incorporating Forecast-Informed Reservoir Operations to increase operational flexibility. These changes aim to improve water supply reliability, environmental flows, and flood risk management.

The U.S. Army Corps of Engineers has initiated a formal update of the Water Control Manual, a process expected to take several years. In the interim, planned deviations will continue to test and refine proposed operational improvements.

More information on efforts to update Truckee Basin reservoir operations is available through the Truckee Water Management Option Pilot Viability Assessment at: https://www.usbr.gov/watersmart/bsp/completed.html

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The Bureau of Reclamation is a federal agency under the U.S. Department of the Interior and is the nation's largest wholesale water supplier and second largest producer of hydroelectric power. Our facilities also provide substantial flood control, recreation opportunities, and environmental benefits.