Higher-than-average releases from all Missouri River Mainstem System projects, including Gavins Point Dam, will continue through November, the U.S. Army Corps of Engineers announced today.

“Gavins Point releases will remain near 80,000 cubic feet per second (cfs) for the remainder of November to ensure flood control storage zones in all system reservoirs are emptied prior to the 2020 runoff season. This release rate is more than twice the average release for this time of the year,” said John Remus chief of the Corps’ Missouri River Basin Water Management Division.

Runoff in all reaches except for the Fort Randall reach was above average for the month of October. The Garrison to Oahe reach runoff was over six times the long-term average and runoff in the Gavins Point to Sioux City reach was more than 10 times the long-term average. The 2019 upper basin runoff forecast was lowered slightly to 60.2 million acre-feet. If realized, this runoff total would be 0.8 MAF less than 2011 (61.0 MAF), which is the highest runoff in 121 years of record-keeping. The January-October observed runoff (56.7 MAF) has already exceeded the second highest runoff, 49.0 MAF observed in 1997, with two months still remaining.

The Missouri River Mainstem Reservoir System total storage was 60.9 MAF as of Nov. 1, occupying 4.8 MAF of the 16.3 MAF flood control zone.

“Because of the high reservoir levels and the forecast for above-average runoff for the remainder of the fall, releases from all System projects will be much above average through November, to evacuate all stored flood waters prior to the start of the 2020 runoff season. We are monitoring the situation very closely and will make any necessary adjustments. Failure to evacuate the stored flood water will lead to increased flood risk in 2020,” said Remus.

Based on the Sept. 1 System storage, winter releases from Gavins Point Dam will be at least 17,000 cfs. Based on the latest reservoir studies, Gavins Point Dam releases will be reduced from 80,000 cfs to 22,000 cfs during December, reaching the winter release rate by the middle of December. Navigation flow support at the mouth of the Missouri River will end on Dec. 11.

Lower release rates must be set during winter months because the Missouri River ices over in the northern reaches limiting the amount of water that can flow beneath the ice.

The Corps will continue to monitor basin and river conditions and will adjust System regulation based on the most up-to-date information.

The comment period for the 2019-2020 Annual Operating Plan ends Nov. 22. The final AOP, which is to be completed in late December, will be posted on the Water Management website: https://www.nwd.usace.army.mil/MRWM/Reports/.

Updates on basin conditions, reservoir levels and other topics of interest can be viewed here: https://www.nwd.usace.army.mil/MRWM/MRWMApp/.

Monthly Water Management Conference Calls

Water management calls include an update from the National Weather Service’s Missouri Basin River Forecast Center, an update on the Missouri River mainstem reservoir system operations, and updates on the ongoing and planned flood recovery efforts in both the Omaha and Kansas City districts. The next call is Thursday, Nov. 7 for Congressional delegations; Tribes; state, county and local government officials, levee and drainage districts; and the media. The last call for 2019 will be held Dec. 5. Calls will be recorded in their entirety and made available to the public on the Defense Video and Imagery Distribution System at www.dvidshub.net/unit/usace-nwd.

Reservoir Forecasts

• Gavins Point Dam
  • Average releases past month – 80,000 cfs
  • Current release rate – 80,000 cfs
  • Forecast release rate – 80,000 cfs
  • End-of-October reservoir level – 1206.7 feet
  • Forecast end-of-November reservoir level – 1206.7 feet
     
• Fort Randall Dam
  • Average releases past month – 75,000 cfs
  • End-of-October reservoir level – 1348.2 feet (down 10.9 feet from September)
  • Forecast end-of-November reservoir level – 1337.8 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 annual drawdown will continue in November.
     
• Big Bend Dam
  • Average releases past month – 60,300 cfs
  • Forecast average release rate – 64,600 cfs
  • Forecast reservoir level – 1420.5 feet
     
• Oahe Dam
  • Average releases past month – 62,100 cfs
  • Forecast average release rate – 65,000 cfs
  • End-of-October reservoir level – 1613.1 feet (falling 2.0 feet during October)
  • Forecast end-of-November reservoir level – 1609.3 feet
     
• Garrison Dam
  • Average releases past month – 47,000 cfs
  • Current release rate – 48,000 cfs
  • Forecast average release rate – 42,000 cfs
  • End-of-October reservoir level – 1842.4 feet (falling 3.3 feet during October)
  • Forecast end-of-November reservoir level – 1839.6 feet
• Notes – Releases will be reduced starting around mid-November reaching 16,000 cfs prior to the river freeze-in at Bismarck. Once an ice cover is established, releases will be gradually increased to 24,500 cfs.
   
• Fort Peck Dam
  • Average releases past month – 14,700 cfs
  • Current release rate – 15,000 cfs
  • Forecast average release rate – 15,000 cfs
  • End-of-October reservoir level – 2240.7 feet (down 2.1 feet from September)
  • Forecast end-of-November reservoir level – 2238.8 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.

The six mainstem power plants generated 1366 million kWh of electricity in October. Typical energy generation for October is 810 million kWh. The power plants are projected to generate 13.1 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://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf.