Gavins Point Dam releases to be reduced to winter release rate in late November

In two virtual public meetings held Nov. 2, U.S. Army Corps of Engineers’ Missouri River Water Management Division presented current hydrologic conditions and planned operation of the Missouri River mainstem reservoir system for the remainder of 2020.

Public meetings are held each fall and spring to update the region on current conditions and planned operations. The Nov. 2 meetings included draft plans for operating the system during 2021.

“We will continue to make releases from Gavins Point Dam to meet full service Missouri River navigation flow targets through the end of the navigation flow support season,” said John Remus, chief of the USACE Missouri River Water Management Division.

Gavins Point release reductions are scheduled to begin around Nov. 22. Releases will be stepped down by approximately 3,000 cubic feet per second each day until reaching the winter release rate of 17,000 cfs.

The navigation flow support season normally ends on Dec. 1 at the mouth of the Missouri River.  Gavins Point Dam winter releases normally range from 12,000 - 17,000 cfs.

Despite cold, snowy weather in October, precipitation was well-below normal in much of the upper basin. The 2020 calendar year runoff forecast for the upper basin, updated on Nov. 2, is 30.2 million acre-feet, 117% of average. Average annual runoff for the upper basin is 25.8 MAF.

As of Nov. 5, the total volume of water stored in the System was 57.1 MAF, occupying 1.0 MAF of the System’s 16.3-MAF flood control zone. System storage peaked at 61.8 MAF on July 16 and is expected to continue to decline in the late fall and winter. All 16.3 MAF of flood control storage is expected to be available prior to the start of the 2021 runoff season.

Most of the basin is experiencing some form of drought. The latest National Drought Mitigation Center drought monitor shows drought degradation over large areas of Montana and North Dakota.  The basin continues to have large areas of Extreme Drought in Colorado, Wyoming, and western Nebraska, with severe to moderate drought in large areas of Montana, North Dakota, South Dakota, Nebraska, and Iowa. 

Navigation

As previously announced, the July 1 System storage check indicated flow support for the second half of the navigation season would be at least at the full-service level for a full-length 8-month flow support season. Full-service flow support is designed to work in tandem with the Missouri River Bank Stabilization and Navigation Project to provide a 9-foot deep by 300-foot wide navigation channel from Sioux City, Iowa to the mouth of the river near St. Louis, Missouri.  Flow support is expected to end on the dates indicated below:

Fall Public Meetings

Recordings of the fall virtual public meetings held Nov. 2 and meeting materials are available online.

Reservoir Forecasts:

• Gavins Point Dam
  • Average releases past month – 33,100 cfs
  • Current release rate – 33,500 cfs (as of Nov. 1)
  • Forecast release rate – 34,500 cfs (November)
  • End-of-October reservoir level – 1207.9 feet
  • Forecast end-of-November reservoir level – 1207.5 feet
  • 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 the winter release rate of 17,000 cfs beginning around Nov. 22 at a rate of 3,000 cfs per day. 
     
• Fort Randall Dam
  • Average releases past month – 30,500 cfs
  • End-of-October reservoir level – 1345.2 feet
  • Forecast end-of-November reservoir level – 1337.5 feet
  • Notes: Releases will be adjusted 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
  • Average releases past month – 21,700 cfs
  • Forecast average release rate – 20,900 cfs
  • Forecast reservoir level – 1420.9 feet
     
• Oahe Dam
  • Average releases past month – 22,300 cfs
  • Forecast average release rate – 20,900 cfs
  • End-of-October reservoir level – 1608.3 feet
  • Forecast end-of-November reservoir level – 1606.6 feet
     
• Garrison Dam
  • Average releases past month – 13,400 cfs
  • Current release rate – 13,000 cfs
  • Forecast average release rate – 13,000 cfs
  • End-of-October reservoir level – 1838.9 feet
  • Forecast end-of-November reservoir level – 1838.4 feet
     
• Fort Peck Dam
  • Average releases past month – 6,000 cfs
  • Current release rate – 6,000 cfs
  • Forecast average release rate – 6,500 cfs
  • End-of-October reservoir level – 2237.3 feet
  • Forecast end-of-November reservoir level – 2236.7 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 732 million kWh of electricity in October. Typical energy generation for October is 820 million kWh. The power plants are projected to generate 10.2 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.