OMAHA, Neb. (KCAU) – Releases at Gavins Point Dam will be increased later this week after seeing an above-average amount of runoff flowing into the Missouri River.
The U.S. Army corps of Engineers held a call Monday updating on the status of releases from the Missouri River Mainstem dams.
John Remus, chief of the Missouri River Basin Water Management Division, told others in the call that Gavins Point Dam was lowered to 60,000 cubic feet per second (cfs) over the weekend so as to help reduce the peak stage between Sioux City and Omaha and prevent overtopping Interstate 29 north of Omaha.
Meanwhile, the Corps is also trying to release water in the flood control storage.
“We have more than half of the flood control storage to evacuate with just over 11 weeks left before we will have to reduce to our winter releases rates,” said Remus.
Starting Wednesday morning, the Corps will increase release by 5,000 cfs every day until they reach 80,000 cfs. Of the 16.3 MAF of total flood storage, 9.0 MAF is occupied. The total system storage also saw an increase of 0.2 MAF since last week.
“These releases are needed to manage reservoir levels and continue evacuating water from the reservoirs,” said Mike Swenson, the team lead for Power Production in the Missouri River Water Management Division.
The National Weather Service reported that areas of eastern Montana, North Dakota, South Dakota and northern Nebraska received four times more precipitation than normal for the first two weeks of September.
“The incredible amounts of rainfall received since the first of September has resulted in major to record flooding along the James, Vermillion, and Big Sioux Rivers. Provisional stage records have been set at 5 South Dakota locations within the James, Vermillion, and Big Sioux basins,” Kevin Low from the NWS’s Missouri Basin River Forecast Center said.
The precipitation has caused excessive runoff to flow into the reservoirs as well as streams below the system, like the James, Vermillion and Big Sioux Rivers.
The Reservoir Regulation in the Missouri River Water Management Division team leader Kevin Grode said that runoff forecast was increased since September 1. The runoff forecast was originally 54.6 MAF for 2019, but with the widespread rains, they revised the forecast to 58.8 MAF, which is twice the average.
“All this rain falling on wet, saturated soils caused by the above-average rains received in July and August has resulted in most of that rain becoming direct runoff – filling up the tributaries, which then drain into the Missouri River upstream of the mainstem projects, and in the case of eastern South Dakota with the James, Vermillion and Big Sioux Rivers, downstream of Gavins Point. We will continue to closely monitor streamflow conditions as some of these tributaries have not yet peaked,” said Grode.
Based on current river forecasts, the four lower Kansas River basin reservoirs will likely be reduced to match inflows to maintain pool elevations or reduced to low flow releases by Thursday. They anticipate emptying stored floodwaters before the end of the year.