For the 2023 calendar year, Missouri River Basin runoff above Sioux City, Iowa totaled 30.4 million acre-feet (MAF), 118% of average. Despite the above average runoff last year, the U.S. Army Corps of Engineers is forecasting below-average runoff into the mainstem reservoir system this year. For 2024, runoff in the Missouri River Basin above Sioux City, Iowa is forecast to be 20.1 MAF, 78% of average.

The 2024 forecast is based on current runoff trends, drier than normal soil conditions, and below-average plains and mountain snowpack. At the start of the 2024 runoff season, which typically begins around March 1, the total volume of water stored in the Missouri River Mainstem Reservoir System (System) is expected to be 53.3 MAF, 2.8 MAF below the top of the carryover multiple use zone. The System is designed to use the water contained within the carryover multiple use zone to support the eight Congressionally authorized purposes during extended droughts. Those purposes are flood control, navigation, water supply, irrigation, hydropower, recreation, water quality control, and fish and wildlife.

“Releases from Gavins Point Dam were reduced to the winter release rate of 13,000 cubic feet per second (cfs) on Dec. 9 and are forecast to remain at that level through the winter season. While releases are 1,000 cfs higher than last year, winter releases remain low in order to conserve water in the System,” said John Remus, Chief of the Missouri River Basin Water Management Division.

There is enough water in the river for all water supply needs. Access to the water remains the responsibility of the facility owners and operators. “Weather and river conditions continue to be monitored and releases from Gavins Point Dam will be adjusted to the extent practical to help mitigate any negative effects of the cold weather. We know the importance of our operations to water supply,” added Remus.

Navigation:

Navigation flow support for the Missouri River is forecast to be 500 cfs below full service for the first half of the 2024 season, which begins April 1 at the mouth of the river near St. Louis, Missouri. The actual service level will be based on the total volume of water stored within the System on March 15, in accordance with the guidelines in the Master Manual. Flow support for the second half of the navigation season, as well as navigation season length, will be based on the storage in the System on July 1.

Mountain and Plains Snowpack:

Mountain snowpack in the upper Missouri River Basin is accumulating at below-average rates. The January 1, mountain snowpack in the Fort Peck reach was 47% of average, while the mountain snowpack in the Fort Peck to Garrison reach was 62% of average. More than half the mountain snowfall typically occurs from January 1 to mid-April, and normally peaks near Apr. 17. The mountain snowpack graphics can be viewed at: http://go.usa.gov/xARQC.  

Final 2023-2024 Annual Operating Plan Released:

The final Annual Operating Plan for the Missouri River Basin for 2023–2024 has been posted at https://www.nwd.usace.army.mil/MRWM/Reports/.

Monthly Water Management Conference Calls Begin for 2024:

The first 2024 monthly conference call will be held Thursday, Jan. 11, to inform basin stakeholders of current weather and runoff forecasts and the planned operation of the reservoir system in the coming months. Presentation materials will be available via webinar. The call is intended for Congressional delegations; Tribes; state, county and local government officials; and the media. It will be recorded in its entirety and made available to the public on our website at https://go.usa.gov/xARQv.

Reservoir Forecasts:

• Gavins Point Dam
  • Average releases past month – 13,400 cfs
  • Current release rate – 13,000 cfs
  • Forecast release rate – 13,000 cfs
  • End-of-December reservoir level – 1208.0 feet
  • Forecast end-of-January reservoir level – 1207.5 feet
  • Notes: The winter release rate will be at least 13,000 cfs and may be adjusted to lessen the impacts of winter ice formation.
     
• Fort Randall Dam
  • Average releases past month – 9,900 cfs
  • End-of-December reservoir level – 1341.0
  • Forecast end-of-January reservoir level – 1344.7 feet
  • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point. The reservoir was drawn down to 1337.5 feet near the end of November 2023 to provide space for winter hydropower generation at Oahe and Big Bend. The reservoir will refill to the base of the flood control pool by the end of February.
     
• Big Bend Dam
  • Average releases past month –10,700 cfs
  • Forecast average release rate – 13,100 cfs
  • Forecast reservoir level – 1420.7 feet
     
• Oahe Dam
  • Average releases past month – 11,000 cfs
  • Forecast average release rate – 12,900 cfs
  • End-of-December reservoir level – 1600.1 feet
  • Forecast end-of-January reservoir level – 1601.1 feet
     
• Garrison Dam
  • Average releases past month – 17,100 cfs
  • Current release rate – 16,000 cfs
  • Forecast release rate – 25,000 cfs
  • End-of-December reservoir level – 1838.7 feet
  • Forecast end-of-January reservoir level – 1837.2 feet
  • Notes – Releases were set at 16,000 cfs in anticipation of the river freeze-in at Bismarck, North Dakota. Once an ice cover is established, releases will be gradually increased to 25,000 cfs to benefit winter hydropower generation and to better balance storage in the upper three reservoirs.
     
• Fort Peck Dam
  • Average releases past month – 5,300 cfs
  • Current release rate – 5,000 cfs
  • Forecast average release rate – 5,000 cfs
  • End-of-December reservoir level – 2229.4 feet
  • Forecast end-of-January reservoir level – 2229.6 feet
  • Notes: Releases will remain at 5,000 cfs in January and February.

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 443 million kWh of electricity in December. Typical energy generation for December is 678 million kWh. Total energy generation for 2023 was 7.9 billion kWh of electricity, compared to the long-term average of 9.4 billion kWh. Forecast generation for 2024 is 8.7 billion kWh.

To view the detailed three-week release forecast for the mainstem dams, go to

http://go.usa.gov/xVgWr.