OMAHA, Neb— The U.S. Army Corps of Engineers-Omaha District is stepping up releases out of Jamestown and Pipestem reservoirs. The current plan is to reach a combined release of 2,400 cubic feet per second by Sunday, Oct. 26. Initial forecasts indicated this release would completely evacuate flood storage by the end of November. However, higher than expected runoff from snowmelt and additional precipitation has increased reservoir forecasts. A combined release of 2,400 cfs will no longer completely evacuate flood storage by the target date of Nov. 25.
USACE has analyzed possible regulation options and associated impacts, including winter releases and/or increased release rates. In order to minimize risk and operate Jamestown and Pipestem dams safely and responsibly, 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 reservoirs.
Temperature forecasts and basin conditions will be closely monitored to determine when releases need to be cut back for ice formation. Once a stable ice cover forms, the Corps plans to incrementally increase releases with the goal of evacuating flood storage before spring runoff begins.
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 above plot shows the U.S. Geological Survey streamgaging station 06470000, James River at Jamestown, North Dakota. The solid black line shows the computed flows since Sept. 1, and is close to the combined reservoir releases. The dotted blue line shows what flows would have been at this location if Jamestown and Pipestem dams were not in place.
Jamestown Dam is currently at a pool elevation of 1436.8 feet, almost 6 feet above the base of the flood control zone, and rising. Inflows into the reservoir spiked yesterday in response to the rainfall, peaking at 3,700 cfs. Inflows have begun to rise again and are currently near 3,800 cfs. The Jamestown Dam release was increased to 1,200 cfs at 1:00 PM today.
Pipestem Dam is currently at a pool elevation of 1469.0 feet, 26.5 feet above the base of the flood control zone, and rising. Inflows into the reservoir spiked yesterday in response to the rainfall, peaking at 4,500 cfs. Inflows have begun to rise again and are currently near 3,700 cfs. Pipestem Dam releases are currently at 800 cfs, and will be increased 100 cfs per day starting tomorrow (Wednesday), reaching the goal of 1,200 cfs on Saturday, Oct. 26.
The Corps of Engineers is coordinating with relevant agencies in North and South Dakota.