Reservoir Flows To Remain Steady
September precipitation was once again below average in the Missouri River Basin. September runoff in the Missouri River Basin above Sioux City, Iowa, was 0.6 million acre-feet, 47 percent of the long-term average. Soil conditions in the upper Missouri River Basin continue to be very dry. According to the Drought Mitigation Center, over 90 percent of the Missouri River basin is currently experiencing some form of abnormally dry conditions or drought, which is almost a 20 percent increase from the end of August.
“Runoff in the upper Missouri River Basin was below average during the month of September and is expected to remain low throughout the rest of 2022,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.
“Releases from Gavins Point Dam will continue to be set to maintain a service level 500 cubic feet-per-second above the minimum service level,” Remus added.
The 2022 calendar year runoff forecast for the upper Basin, updated on Oct. 1, is 19.5 MAF, 76 percent of average and 0.7 MAF lower than last month’s annual runoff forecast. Average annual runoff for the upper Basin is 25.7 MAF.
Total System storage as of Oct. 5 was 48.5 MAF, which is 7.6 MAF the base of the flood control zone. Due to the extremely dry conditions in the upper Missouri River Basin, the System is expected to lose an additional 2.0 MAF before the 2023 runoff season begins in March of 2023.
As per the criteria in the Maser Manual, the winter release rate is determined based on the Sept. 1 System storage. Per the Sept. 1 System storage, winter releases from Gavins Point Dam will be at the minimum rate of 12,000 cfs. In anticipation of the low winter releases, a letter was sent in early July to all water users below Gavins Point Dam making them aware of the planned releases, and encouraging them to assess the risk to their facilities. The volume of water in the Missouri River downstream of the System will be adequate for water supply needs. However, the USACE cannot guarantee access to the water. Access to the water is the responsibility of the individual intake owner/ operators.
At Fort Peck Dam, average releases for the past month were 7,700 cfs; current release rate is 4,000 cfs; forecast average release rate is 4,100 cfs; End-of-September reservoir level was 2219.7 feet; forecast end-of-October reservoir level is 2219.5 feet. The forecast reservoir releases and elevations discussed above are not definitive. Additional precipitation, lack of precipitation or other circumstances could cause adjustments to the reservoir release rates.
The six mainstem power plants generated 832 million kWh of electricity in September. Typical energy generation for September is 902 million kWh. The power plants are projected to generate 7.4 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh.
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