OMAHA, Neb. (KCAU) – To reduce the chance of flooding downstream, releases at Gavins Point Dam will be lowered for a few days and then increased.
The U.S. Army Corp of Engineers said in a Friday news release that releases at the Gavins Point Dam near Yankton, South Dakota will be brought down 5,000 cubic feet per second (cfs) Saturday. It will then be brought down another 5,000 cfs Sunday to 60,000 cfs and stay there for no more than three days.
The cause for lowering releases is to hopefully lower peak flood stage forecast on the Missouri River between Sioux City, Iowa and Omaha, Nebraska.
“We are reducing releases from Gavins Point Dam to try to reduce the chances of floodwater reaching Interstate 29 north of Omaha,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division.
Rainfall in September brought between 200 and 600% of normal rainfall over the entire Missouri River Basin, and the National Weather Service issued river several river flood alerts and warnings due to it.
“We have already seen four times the normal precipitation for September over the entire upper Missouri River basin,” said Remus.
After the lower releases at Gavins Point, the Corps will incrementally increase release by 5,000 cfs a day up to a total of 80,000 cfs. They want to ensure that the 16.3 Million Acre Feet (MAF) of flood storage is free before the 2020 runoff season.
Runoff for the Missouri River Basin about Sioux City reached 49.9 MAF as of Friday, making it the second-highest runoff in record. Runoff for 2019 was forecast on September 1 to be 54.6 MAF, but the projected runoff is now 58.8 MAF.
Since September 1, runoff into the Big Bend, Fort Randall and Gavins Point reservoirs, as well as the unregulated James and Vermillion Rivers in South Dakota and the Big Sioux River in South Dakota and Iowa have seen between 3-8 inches of rainfall.