Water releases from Gavins Point Dam increased to 90,000 cubic feet per second Thursday night as unregulated inflows from the Niobrara and other watersheds continue to spill into the reservoir according to the U.S. Army Corps of Engineers.
Operators at Gavins Point are using 12 of the 14 spillway bays and the powerhouse to pass the flows. The remaining two spillway gates are partially open, but frozen in place due to ice buildup. Operators are spilling water over those two gates in an effort to thaw them and return them to operating condition, which dam safety engineers believe presents no risk to the structure or the gates nor does it affect the Corps’ ability to safely pass water pass the structure.
The water being released from Gavins Point is exclusively from unregulated tributaries that bring water into the reservoir. On Wednesday, the Corps stopped all releases from Fort Randall Dam, the next dam upstream on the Missouri River mainstem, to reduce the amount of water in the lower Missouri River.
However, because there is very little storage capacity behind Gavins Point, most of what is flowing into the reservoir must be released downstream. Despite these efforts, communities from Sioux City, Iowa to St. Louis continue to experience flooding, or the threat of flooding, due to runoff from the numerous rivers and creek through the lower section of the river.
Emergency managers and engineers from the Corps’ Omaha and Kansas City districts are supporting state and local authorities with levee monitoring and other flood response activities, to include technical advice and sand bag distribution.
“Given the amount of water still expected to come out of the tributaries, we expect we will hold at 90,000 cfs through Saturday morning, provided the current inflow trend are maintained” says John Remus, chief of the Corps’ Missouri River Water Management Division in Omaha. “As that unregulated runoff decreases, we will be able to decrease outflows from Gavins Point.”
Remus cautioned, however, that river levels could remain high in places for several days to a week as conditions in the different basins normalize.
Much of the Corps’ ability to capture and store runoff is in South Dakota, North Dakota and Montana, at the reservoirs impounded by Oahe, Garrison and Fort Peck dams. Had this weather system tracked further north, the Corps may have been in a better position to reduce some of the flow in the lower Missouri River, Remus added.