As part of the normal operation of the Mainstem Reservoir System, the U.S. Army Corps of Engineers (Corps) Missouri River Basin Water Management Division has reduced releases from several Missouri River dams to winter levels.  

Due to robust runoff in the Missouri River basin this year, flow support for navigation was extended 10-days, ending on Dec. 10 at the mouth.  “Daily releases from Fort Randall and Gavins Point dams were reduced to normal winter levels in a stair-step manner between Dec. 1 and 8 marking the end of the 2014 navigation flow support,” says Jody Farhat, chief of the Missouri River Basin Water Management Division. “Our reservoir release plans during the winter will provide good service to downstream water users and ensure we have the entire flood control capacity available next year.”  

The 2014 calendar year runoff forecast is 34.5 million acre feet (MAF), 137 percent of normal.  Average annual runoff is 25.2 MAF. Runoff during the month of November was 83 percent of normal due in part to cold weather freezing many of the tributaries, which reduced inflow into the reservoir system.  The total volume of water stored in the reservoir system at the end of November was 56.5 MAF, down 1.6 MAF for the month. Currently, less than 0.5 MAF of the 16.3 MAF combined flood control storage is occupied.  The remaining stored flood waters will be evacuated during the winter, and all flood control storage will be available by the start of the 2015 runoff season. 

During the winter, the Corps will closely monitor conditions throughout the basin and make reservoir regulation adjustments to lessen the impact of river ice formation.  In late November, releases from Garrison Dam were reduced to 16,000 cfs in anticipation of ice formation. Garrison releases will remain at this level in December, and conditions permitting, will increase to 19,500 cfs in January. 

Reservoir Forecasts  

Gavins Point Dam releases averaged 38,300 cfs for the month of November.  Flows were reduced to 17,000 cfs between Dec. 1 and 8.  All winter releases will be made through the powerhouse. The reservoir elevation behind Gavins Point Dam ended November at 1207.8 feet and will remain near its normal seasonal pool elevation of 1207.5 feet in December. 

Fort Randall Dam releases averaged 37,800 cfs in November.  Releases will be adjusted during the remainder of the month to maintain the desired elevation at Gavins Point. The reservoir ended November at elevation 1337.5 feet, down 7.3 feet and will be refilled during the winter to increase winter hydropower generation at Oahe and Big Bend dams. 

Big Bend Dam releases averaged 28,600 cfs during the month of November. December releases will average approximately 19,300 cfs.  The reservoir will remain near its normal elevation of 1420 feet during December. 

Oahe Dam releases averaged 31,300 cfs during November.  December releases will average approximately 18,800 cfs. The reservoir ended November at elevation 1607.9 feet, down 1.8 feet.  The pool is expected to fall less than 1 foot in December. 

Garrison Dam releases averaged 20,300 cfs during November.  Releases will remain at 16,000 cfs in December, and conditions permitting, will increase to 19,500 cfs in January.  The reservoir behind Garrison ended November at elevation 1840.9 feet, down 2 feet, and expected to drop about 1 foot during December. 

Fort Peck Dam releases averaged 5,000 cfs for the month of November.  Releases were increased to 6,000 cfs on Dec. 3. The reservoir ended November at elevation 2233.2 feet, up 0.2 feet from the previous month, but still nearly 1 foot below the base of the annual flood control zone. The reservoir is forecast to maintain a nearly steady pool during December. 

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. To view the detailed three-week release forecast for the mainstem dams, go to https://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf.  

The six mainstem power plants generated 890 million kilowatt hours (kWh) of electricity in November. Typical energy generation for the month of November is 738 million kWh. The power plants are projected to generate 9.6 billion kWh of electricity this year, compared to the normal 10 billion kWh, which provides enough energy to power nearly one million homes. 

The 2014–2015 Missouri River Annual Operating Plan will be published later this month and will be available online at https://www.nwd-mr.usace.army.mil/rcc/reports/rcc_publications_reports.html.  

The Corps is congressionally authorized to manage the six dams on the Missouri River for the benefit of the American people serving flood control, navigation, hydropower, irrigation, water supply, water quality control, recreation, and fish and wildlife.   

MISSOURI RIVER MAINSTEM RESERVOIR DATA 

WATER RELEASES AND ENERGY GENERATION FOR NOVEMBER