Posted on January 9, 2023
For the 2022 calendar year, Missouri River basin runoff above Sioux City, Iowa totaled 19.3 million acre-feet, 75% of average. This was the 30th lowest annual runoff for the Missouri River Basin in 125 years of record-keeping.
The ongoing drought shows little relief in sight and the U.S. Army Corps of Engineers predicts runoff into the mainstem reservoir system will remain below normal. For 2023, runoff in the Missouri River basin above Sioux City, Iowa is forecast to be 20.8 MAF, 81% of average.
This is based on current runoff trends, drier than normal soil conditions, and nearly average plains and mountain snowpack. At the start of the 2023 runoff season, which typically begins around March 1, the total volume of water stored in the mainstem reservoir system is expected to be 45.7 MAF, 10.4 MAF below the top of the carryover multiple use zone. The Mainstem Missouri River reservoir system is designed to use the water contained within the carryover multiple use zone to provide service to 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.
Service to the authorized purposes will continue to be reduced to conserve water in the reservoir system should drought conditions persist. Primary drought conservation measures outlined in the Master Manual include reducing winter releases and flow support for navigation. Flow support to navigation was provided at or near the minimum service level throughout the 2022 season. A significant portion of the water stored in the multiple use zone was used in 2021 and 2022 to serve the authorized purposes and resulted in implementation of water conservation measures.
To further conserve water in the Missouri River Mainstem reservoir system, minimum releases from Gavins Point Dam are scheduled this winter while still serving the needs of the municipal, industrial and powerplant water intakes along the lower river.
While the winter target release from Gavins Point Dam is 12,000 cfs, releases were increased to 14,000 cfs in mid-December and early January to mitigate some of the effects of the much colder temperatures across the lower basin. Releases are currently at 14,000 cfs.
Releases from Gavins Point Dam will be reduced beginning Jan. 9, by 1,000 cubic feet per second to 13,000 cfs and held for three days and reduced to 12,000 cfs on Jan 12.
“With weather conditions and river stages forecast to be more seasonal in over the next few weeks, we are restoring system releases to the minimum winter rates,” 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 owner operators.
Weather and river conditions continue to be monitored.
“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 flow support for the Missouri River is forecast to be at minimum service for the first half of the 2023 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 slightly above-average rates. The Jan. 1, mountain snowpack in the Fort Peck reach was 111% of average, while the mountain snowpack in the Fort Peck to Garrison reach was 103% of average. More than half the mountain snowfall typically occurs from Jan. 1 to mid-April, and normally peaks near April 17. The mountain snowpack graphics can be viewed at: http://go.usa.gov/xARQC.
The plains snowpack, which typically melts from mid-February into April, is currently above normal. Over 2 inches of snow water equivalent (SWE) covers much of the plains, with up to 6 inches in the central Dakotas and in the upper James River basin in North Dakota.
Final 2022-2023 Annual Operating Plan Released:
The final Annual Operating Plan for the Missouri River Basin for 2022–2023 has been posted at https://www.nwd.usace.army.mil/MRWM/Reports/.
Monthly Water Management Conference Calls Begin for 2023:
The first 2023 monthly conference call will be held Thursday, Jan. 12, 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.
- Gavins Point Dam
- Average releases past month – 13,500 cfs
- Current release rate – 14,000 cfs
- Forecast release rate – 12,000 cfs
- End-of-December reservoir level – 1206.8 feet
- Forecast end-of-January reservoir level – 1207.5 feet
- Notes: The winter release rate will be at least 12,000 cfs and may be adjusted to lessen the impacts of winter ice formation.
- Fort Randall Dam
- Average releases past month – 12,000 cfs
- End-of-December reservoir level – 1338.7
- Forecast end-of-January reservoir level – 1344.5 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 2022 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 – 13,000 cfs
- Forecast average release rate – 17,000 cfs
- Forecast reservoir level – 1420.8 feet
- Oahe Dam
- Average releases past month – 13,100 cfs
- Forecast average release rate – 17,100 cfs
- End-of-December reservoir level – 1589.7 feet
- Forecast end-of-January reservoir level – 1591.3 feet
- Garrison Dam
- Average releases past month – 17,600 cfs
- Current release rate – 22,000 cfs
- Forecast average release rate – 23,500 cfs
- End-of-December reservoir level – 1830.3 feet
- Forecast end-of-January reservoir level – 1827.7 feet
- Notes – Releases were set at 16,000 cfs prior to the river freeze-in at Bismarck, North Dakota. Releases are being gradually increased to 23,500 cfs as downstream conditions permit to benefit winter hydropower generation and to better balance storage in the upper three reservoirs.
- Fort Peck Dam
- Average releases past month – 5,700 cfs
- Current release rate – 6,000 cfs
- Forecast average release rate – 6,500 cfs
- End-of-December reservoir level – 2218.8 feet
- Forecast end-of-January reservoir level – 2218.4 feet
- Notes: Releases will remain at 6,500 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.
The six mainstem power plants generated 475 million kWh of electricity in December. Typical energy generation for December is 682 million kWh. Total energy generation for 2022 was 7.5 billion kWh of electricity, compared to the long-term average of 9.4 billion kWh. Forecast generation for 2023 is 7.7 billion kWh.
To view the detailed three-week release forecast for the mainstem dams, go to http://go.usa.gov/xVgWr.