With Little Water Storage During Flooding, Corps of Engineers Takes Rare Steps
By Nick Hytrek
The U.S. Army Corps of Engineers will increase water releases from Gavins Point Dam this week to clear room for runoff from melting snow in the Dakotas.
Releases from the dam near Yankton, South Dakota, are scheduled to be raised Wednesday from 39,000 cubic feet per second to 42,000 cfs. Releases will then be increased incrementally daily until reaching 55,000 cfs on Sunday. Releases are to remain at that level until April 14, depending on weather conditions.
Melting snow in North Dakota and South Dakota has begun to flow into the lower Missouri River reservoirs at Oahe and Fort Randall dams, both upstream of Gavins Point. The increased releases from Gavins Point will enable the corps to respond to rainfall events while snow continues to melt.
"The spring runoff season is just beginning. Having very high pools in the lower reservoirs at this time of year severely limits the corps' ability to respond to rainfall events that may occur anywhere in the (Missouri River) basin. To provide for the greatest degree of flood risk reduction throughout the runoff season, it is important to create some room in (Oahe and Fort Randall)," John Remus, chief of the corps' Missouri River Water Management Division in Omaha, said in a news release.
As of Monday, storage in the Missouri River's six reservoirs totaled 62.6 million acre-feet, and 6.5 MAF of the system's 16.3 MAF of flood control storage was occupied. Snowmelt and large inflows are expected to continue during the coming week, and soils have begun to thaw but still have a lot of frost left, the corps said.
Gavins Point releases were increased significantly in mid-March when rain and melting snow inundated the Niobrara River and other waterways that flow into Lewis and Clark Lake behind Gavins Point Dam. The lake's elevation peaked at a record 1212.3 feet on March 15 and has since decreased to 1205.9 feet.
(c)2019 Sioux City Journal, Iowa