The U.S. Army Corps of Engineers' current plan to reach a combined water release from the Jamestown and Pipestem dams of 2,400 cubic feet per second will no longer completely evacuate flood storage by the target date of Nov. 25, the Corps said.
The Jamestown Dam releases were increased to 1,200 cfs on Monday, Oct. 21, and Pipestem Dam is expected to increase in increments of 100 cfs starting Wednesday, Oct. 23, to reach 1,200 cfs by Saturday, Oct. 26.
The Corps said higher than expected runoff from snowmelt and additional precipitation has caused both reservoirs to rise substantially.
On Oct. 22, the Corps said Jamestown Dam was at a pool elevation of 1,436.8 feet and rising, which is nearly 6 feet above the base of the flood control zone. Inflow into the reservoir was at 3,700 cfs on Oct. 21.
Pipestem Dam was reported to be at a pool elevation of 1,469 feet and rising, which is 26.5 feet above the base of the flood control zone. Inflow into the reservoir on Oct. 21 was 4,500 cfs.
The Corps said possible regulation options have been analyzed, including winter releases and increased release rates, but the Corps plans to continue releases at the combined release rate of 2,400 cfs for the fall until ice forms on the river and the reservoirs.
Officials will closely monitor temperature forecasts and basin conditions to determine when releases need to be cut back for ice formation. Once stable ice cover forms, the Corps plans to incrementally increase water releases with the goal of evacuating flood storage before spring runoff begins.
The Corps said ice conditions in the entire James River basin will continuously be evaluated throughout the winter. The Corps will operate to minimize the risk of ice-related flooding, and adjustments to the releases will be made as needed.
The Corps of Engineers said it is coordinating with relevant agencies in North and South Dakota.