Gavins Point Dam releases to be reduced to winter release rate

Photo By Eileen Williamson | Missouri River monthly update for November showing the system storage and reservoir storage comparison charts for the Missouri River Mainstem System and the "big three" dams of Fort Peck, Garrison, and Oahe Dam. Winter releases from Gavins Point Dam for the 2023-2024 winter will be slightly higher than last winter, which were at the minimum rate. Intake operators in the lower river should be taking measures to assure they can maintain access to the water.  

OMAHA, NE, UNITED STATES

11.06.2023

Story by Eileen Williamson 

U.S. Army Corps of Engineers, Northwestern Division

Gavins Point Dam releases will be reduced in late November as flow support to navigation ends. Releases are currently 32,000 cubic feet per second.
“We will continue to make releases from Gavins Point Dam to provide flow support at an intermediate service level, 1,500 cfs less than full service, through the end of the navigation flow support season,” said John Remus, chief of the USACE, Missouri River Water Management Division. “The flow support season will end on Dec. 1 at the mouth of the Missouri River.”
Release reductions to the winter rate of 13,000 cfs are scheduled to begin around Nov. 22. Releases will be gradually reduced by 3,000 cfs each day until reaching a rate of 15,000 cfs. Releases will then be paused before stepping down 1,000 cfs every five days to the winter release. Fort Randall releases will be stepped down in a similar manner, approximately one day prior to the Gavins Point reductions.
“Winter releases from Gavins Point Dam for the 2023-2024 winter will be slightly higher than last winter, which were at the minimum rate,” said Remus. “Intake operators in the lower river should be taking measures to assure they can maintain access to the water.”
October runoff in the Missouri River basin above Sioux City, Iowa, was 1.5 million-acre-feet (MAF), which is 124% of normal. Runoff was above average in every reach except Sioux City, which was below average. Based on the most recent seasonal drought outlook, drought conditions are expected to persist through the end of January in the upper Basin, with a potential for improvement in the lower Basin. The 2023 calendar year runoff forecast for the upper Basin, updated on Nov. 1, is 29.8 MAF, 116% of average.
Reservoir studies indicate System storage will be below normal at the start of the 2024 runoff season. System storage is forecast to be about 52.9 MAF, which is 3.2 MAF into the System’s Carryover and Multiple Use Zone. This means that the Fort Peck, Garrison, and Oahe reservoirs are expected to be approximately four to five feet below the base of their respective flood control zones on March 1.


Navigation
As previously announced, the July 1 System storage check indicated a full-length flow support season but at an intermediate flow support level, 1,500 cfs below full-service, for the second half of the 2023 navigation season. Flow support is expected to end on the dates indicated below:
Location End Date
Sioux City, Iowa Nov. 22
Omaha, Nebraska Nov. 24
Nebraska City, Nebraska Nov. 25
Kansas City, Missouri Nov. 27
Mouth near St. Louis, Missouri Dec. 1
 

Reservoir Forecasts:
• Gavins Point Dam
o Average releases past month – 34,100 cfs
o Current release rate – 32,000 cfs (as of Nov. 1)
o Forecast average release rate – 29,000 cfs (November)
o End-of-October reservoir level – 1207.6 feet
o Forecast end-of-November reservoir level – 1207.6 feet
o Notes: Releases will be adjusted as necessary to meet all downstream navigation targets until the end of the navigation flow support season. The Gavins Point release will be reduced to 15,000 cfs beginning around Nov. 22 at a rate of 3,000 cfs per day, then at a rate of 1,000 cfs every 5 days to the winter release rate of 13,000 cfs.
• Fort Randall Dam
o Average releases past month – 30,800 cfs
o End-of-October reservoir level – 1346.7 feet
o Forecast end-of-November reservoir level – 1337.5 feet
o Notes: Releases will be stepped down near the end of November, approximately one day prior to the Gavins Point reductions as necessary to maintain the desired reservoir elevation at Gavins Point. The Fort Randall pool is normally drawn down to 1337.5 feet in the fall to provide space for winter hydropower generation at Oahe and Big Bend. The annual drawdown will continue in November.
• Big Bend Dam
o Average releases past month – 21,800 cfs
o Forecast average release rate – 16,500 cfs
o Forecast reservoir level – 1420.6 feet
• Oahe Dam
o Average releases past month – 21,600 cfs
o Forecast average release rate – 16,300 cfs
o End-of-October reservoir level – 1599.0 feet
o Forecast end-of-November reservoir level – 1599.2 feet
• Garrison Dam
o Average releases past month – 17,000 cfs
o Current release rate – 17,000 cfs
o Forecast average release rate – 17,000 cfs
o End-of-October reservoir level – 1840.1 feet
o Forecast end-of-November reservoir level – 1839.4 feet
• Fort Peck Dam
o Average releases past month – 4,800 cfs
o Current release rate – 4,500 cfs
o Forecast average release rate – 4,500 cfs
o End-of-October reservoir level – 2228.9 feet
o Forecast end-of-November reservoir level – 2229.1 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.

Hydropower:
The six mainstem power plants generated 752 million kWh of electricity in October. Typical energy generation for October is 814 million kWh. The power plants are projected to generate 7.9 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.

• Date Taken: 11.06.2023
• Date Posted: 11.06.2023 13:29
• Story ID: 457292
• Location: OMAHA, NE, US