The U.S. Army Corps of Engineers began reducing the Gavins Point releases to the winter release rate on Nov. 23 with the navigation flow support season ending on Dec. 1 at St. Louis.

“Releases from Gavins Point Dam are being reduced to the 12,000 cubic feet per second winter release rate by mid-December,” said John Remus, Chief of the Missouri River Water Management Division.

“We will closely monitor river conditions, and releases will be adjusted to the extent practical to lessen the impacts of river ice formation on stages in the lower river.”  Releases were at 32,000 cfs prior to the reductions.

As the colder, winter temperatures enter the basin, USACE will closely monitor Missouri River ice conditions between the System reservoirs and downstream of Gavins Point Dam for potential ice jams that could impact river stages and water intakes.

Runoff in the upper Missouri River Basin above Sioux City, Iowa, was 0.7 million acre-feet during November, 67% of average. The 2024 calendar year runoff forecast is 22.9 MAF, 89% of average. Average annual runoff is 25.7 MAF.

The total volume of water stored in the Missouri River mainstem reservoirs on Nov. 30 was 50.4 MAF, which is 5.7 MAF below the base of the System flood control storage zone. System storage is forecast to begin the 2025 runoff season at 50.2 MAF, which is 5.9 MAF below the base of the system flood control zone.  

Releases from Fort Peck Dam are currently 5,500 cfs and are forecasted to be increased to 6,500 cfs in January and February. Releases from Garrison Dam were increased from 14,000 cfs to 16,000 cfs in late November.  Releases are forecasted to remain at 16,000 cfs until the formation of a stable river ice cover at Bismarck, North Dakota.  Then releases will be gradually increased to 22,000 cfs, downstream conditions permitting. Releases from Garrison are typically set near 16,000 cfs prior to the river freeze-in to reduce the risk of ice-induced flooding in the Bismarck area. Releases at Fort Peck and Garrison dams are being adjusted as part of balancing storage in the upper reservoirs.

Mountain and Plains Snowpack

Mountain snowpack in the upper Missouri River Basin is accumulating at below average levels. About 25% of the mountain snowpack typically accumulates by Dec. 1, and normally peaks in mid-April. The mountain snowpack graphics can be viewed here: http://go.usa.gov/xE6wT. Currently, plains snowpack in the upper Missouri River Basin is sparse.

2024-2025 Annual Operating Plan

The comment period for the 2024-2025 Annual Operating Plan ended in November. The final AOP is scheduled for publication by the end of 2024 and will be posted on the Water Management website: https://www.nwd.usace.army.mil/MRWM/Public-Meetings/.

Reservoir Forecasts

• Gavins Point Dam
  • Average releases past month – 29,100 cfs
  • Current release rate – 14,000 cfs
  • Forecast release rate – 12,000 cfs
  • End-of-November reservoir level – 1207.8 feet
  • Forecast end-of-December reservoir level – 1207.5 feet
  • Notes: Releases were reduced to 14,000 cfs on Dec. 3. The winter release rate will be 12,000 cfs based on the Sept. 1 System storage check and may be adjusted to lessen the impacts of winter ice formation.
     
• Fort Randall Dam
  • Average releases past month – 26,900 cfs
  • End-of-November reservoir level – 1338.4 feet (down 5.5 feet during November)
  • Forecast end-of-December reservoir level – 1339.2 feet
  • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point. The reservoir is normally drawn down to 1337.5 feet in the fall to provide space for winter hydropower generation at Oahe and Big Bend.  The reservoir will refill to the base of the flood control pool from December to February.
     
• Big Bend Dam
  • Average releases past month – 22,100 cfs
  • Forecast average release rate – 12,500 cfs
  • Forecast reservoir level – 1420.8 feet
     
• Oahe Dam
  • Average releases past month – 22,300 cfs
  • Forecast average release rate – 12,400 cfs
  • End-of-November reservoir level – 1596.2 feet (down 1.8 feet during November)
  • Forecast end-of-December reservoir level – 1597.1 feet
     
• Garrison Dam
  • Average releases past month – 14,100 cfs
  • Current release rate – 16,000 cfs
  • Forecast average release rate – 17,600 cfs
  • End-of-November reservoir level – 1836.4 feet (down 1.1 feet during November)
  • Forecast end-of-December reservoir level – 1834.4 feet
  • Notes – Releases will be set near 16,000 cfs prior to the river freeze-in at Bismarck, North Dakota. Once an ice cover is established, releases will be gradually increased to 22,000 cfs.
     
• Fort Peck Dam
  • Average releases past month – 4,500 cfs
  • Current release rate – 5,500 cfs
  • Forecast average release rate – 5,500 cfs
  • End-of-November reservoir level – 2226.5 feet (down 0.3 feet during November)
  • Forecast end-of-December reservoir level – 2225.7 feet
  • Notes: Releases will remain at 5,500 cfs in December. Releases will be increased to 6,500 cfs in January.

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.

Hydropower

The six mainstem power plants generated 645 million kWh of electricity in November. Typical energy generation for November is 741 million kWh. The power plants are projected to generate 8.2 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh.

To view the detailed three-week release forecast for the mainstem dams, go to http://go.usa.gov/xVgWr.