SOUTH SIOUX CITY -- Conditions at South Sioux City's Scenic Park have returned to normal after a brief bout with flooding in late June.
But city officials will keep an eye on Missouri River levels, especially now that more water will be released from the river's reservoirs.
The U.S. Army Corps of Engineers on Friday said releases would be increased from Gavins Point Dam upstream near Yankton, South Dakota, to approximately 60,000 cubic feet per second because of heavy rainfall and a higher-than-average amount of melting mountain snow running into the river upstream.
The releases will be increased as the amount of water pouring into the Missouri from other rivers as a result of recent heavy rains begins to decrease. Gavins Point releases will remain around 60,000 cfs through November. Releases Monday were at 48,200 cfs, according to the corps' daily river bulletin.
Torrential rainfalls in southeast South Dakota, northwest Iowa and southwest Minnesota in recent weeks filled the Vermillion, James and Big Sioux rivers, which empty into the Missouri River downstream of Gavins Point. The influx from those tributaries caused the Missouri river to rise to 26 feet at Sioux City, leading to the flooding at Scenic Park across the river in South Sioux City.
The Missouri River was at 21.5 feet Monday, and South Sioux City Parks and Recreation director Gene Maffit said Monday that it was of little concern, even with forecasts calling for it to rise to 22 feet before dropping later in the week. Maffit said there is still some water under a walking bridge in the park, but the river must reach 26 feet before it tops the bank near Scenic Park and floods.
Maffit said he'd keep an eye on the river as the corps steps up releases from Gavins Point.
The corps has increased the 2018 runoff forecast to 39.8 million acre feet above Sioux City, 157 percent of average. The forecast was up from June's prediction of 34.6 MAF. June's runoff totaled 10 MAF, the third highest monthly runoff in 120 years of records.
Rainfall and melting mountain snowpack have filled up 11.7 MAF of the 16.3 MAF flood control zone in the river's six reservoirs, leaving about 25 percent of the system's flood control storage available.
The mountain snowpack is nearly all melted, and system storage should peak in mid July, said John Remus, chief of the corps' Missouri River Basin Water Management Division. He said that the 11.7 MAF of water in flood storage as of July 1 compared to 16 MAF in storage on that date in 2011, when damaging flooding was widespread in the river valley.
"The current amount of vacant flood control storage provides flexibility to lessen downstream flooding should suddenly developing large rainfall events occur anywhere in the basin," Remus said in a news release.