The U.S. Army Corps of Engineers will temporarily increase discharges out of Gavins Point Dam on Tuesday to conduct a spillway flow test.
The spillway was damaged in the 2011 Missouri River flood, and the test will provide information on the current condition of the spillway.
Starting at 7:30am releases will be ramped up from 14,000 to 26,000 cubic feet per second. The releases may be increased to 40,000 cfs for short periods of time. The total test period is not expected to exceed 8 hours.
At the completion of the test, total releases will be reduced back to 14,000 cfs.
The impact to the river stage in Sioux City should result in a rise of 3-point-4 feet starting from just before midnight Tuesday night and peaking at 4 pm Wednesday afternoon.