The US Army Corps of Engineers will increase releases from Gavins Point Dam at Yankton to 75,000 cubic feet per second tomorrow (Sat.).
Chief of the Missouri River Basin Water Management Division John Remus says runoff into the upper Missouri River above Sioux City has remained high and rain continues to fall in the places it’s not needed. He says the rainfall runoff continues to flow into the Oahe, Big Bend, Fort Randall and Gavins Point reservoirs at significantly higher than average rates.
Remus says runoff for the month upstream of Sioux City, Iowa is more than 7.5 million acre feet, more than double the long-term average (3.3 maf). He says to provide some relief for the Oahe and Fort Randall reservoirs, the Corps has reduced flows from Garrison Dam to 15,000 cfs to offset some of the high flows entering the system. Both Oahe and Fort Randall are storing water in their exclusive flood control zones.
Releases will remain higher than average into the fall because the reservoirs have to be at the base of the annual flood control pool by the beginning of the 2020 runoff season.
Oahe: (Storing in Exclusive Flood Control Zone)
Total Flood Control Storage: 4.315 MAF
Current Flood Control Storage: 3.68 MAF (85.3% filled)
Pool level: 1618.29 ft (Top of flood control – 1620 ft)
Inflows: 65,000 cfs
Releases: 30,000 cfs (June 1 37,000 cfs; June 2 40,000 cfs; June 3 48,000 cfs)
Big Bend: (Big Bend is a re-regulation project and has very limited flood control storage)
Total Flood Control Storage: 0.179 MAF
Current Flood Control Storage: 0.665 MAF (37.2% filled)
Pool level: 1421.16 ft (Top of flood control – 1423 ft)
Inflows: 50,000 cfs
Releases: 47,000 cfs (June 3 50,000 cfs)
Fort Randall: (Storing in Exclusive Flood Control Zone)
Total Flood Control Storage: 2.292 MAF
Current Flood Control Storage: 1.733 MAF (75.6% filled)
Pool level: 1369.41 ft (Top of flood control – 1375 ft)
Inflows: 79,000 cfs
Releases: 60,000 cfs (May 31 65,000 cfs; June 1 68,000 cfs)
Gavins Point: (Gavins Point is a re-regulation project and has very limited flood control storage)
Total Flood Control Storage: 0.133 MAF
Current Flood Control Storage: 0.042 MAF (31.4% filled)
Pool level: 1206.47 ft (Top of flood control – 1210 ft)
Inflows: 68,000 cfs
Releases: 70,000 cfs (Going to 75,000 cfs Saturday, June 1 at 8 a.m.)
