Omaha, Neb. — The Missouri River mainstem reservoir system has the full flood control zone capacity available for the 2015 runoff season because all of the previously stored flood waters have been evacuated, according to the U.S Army Corps of Engineers (Corps) Missouri River Water Management Division.  

“The last remaining 2014 flood water was evacuated in early January when the combined storage in the reservoirs fell below 56.1 million acre feet (MAF), the base of the flood control zone,” said Jody Farhat, chief of the Missouri River Basin Water Management Division.  “The entire flood control capacity of the mainstem reservoir system is ready to capture runoff in the spring, reducing flood risk while providing good support to the other authorized project purposes.” 

Based on the current soil moisture and mountain snowpack conditions, the 2015 forecast runoff in the Missouri River Basin above Sioux City, Iowa, is 25.5 MAF, 101 percent of normal. Normal runoff is 25.2 MAF.  January runoff into the Missouri River Basin above Sioux City, Iowa, was 178 percent of normal. Runoff typically slows during winter months as snow accumulates and rivers freeze, reducing inflows into the reservoir system.  However, warmer-than-normal temperatures during the last half of January melted plains snow and river ice, resulting in above normal runoff for the month. 

“Because of the warm temperatures, system storage climbed in late January, ending the month at 56.5 MAF, 0.4 MAF above the base of the annual flood control zone,” said Farhat. “Typically, this inflow would occur in early spring; it came a bit early this year but doesn’t impact the reservoir system’s ability to reduce flood risk.” 

As of Feb. 5, the mountain snowpack was 95 percent of normal in the reach above Fort Peck Dam and 101 percent of normal in the reach from Fort Peck to Garrison dams.  Mountain snowpack will continue to accumulate during the next few months and normally peaks in mid-April. View the mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf. 

“Currently, the mountain snowpack and runoff forecast are near average, but there are more than two months remaining in the snowpack accumulation season,” said Farhat.  “We will continue to monitor basin conditions through the winter and into spring and will fine tune the regulation of the reservoir system based on the most up-to-date information.” 

Reservoir forecasts  

Gavins Point Dam releases averaged 19,100 cubic feet per second (cfs) during January; normal winter releases are 17,000 cfs.  Releases will remain near that level through mid-March when they will be stepped up to provide support for the 2015 navigation season, which will open on April 1 at the mouth of the Missouri River near St. Louis, Mo. Flow support for Missouri River navigation will be full service for the first half of the navigation season in accordance with guidelines in the Master Manual. Flow support for the second half of the navigation season as well as the navigation season length will be set based on the July 1 system storage. The reservoir behind Gavins Point Dam ended January at elevation 1208.1 feet.  The reservoir will be drawn down to 1206.0 feet by early March in anticipation of the upcoming spring runoff season. 

Fort Randall Dam releases averaged 17,600 cfs during January. Releases will be adjusted as necessary to maintain the elevation at Gavins Point. The reservoir ended January at elevation 1346.0 feet. It is forecast to reach elevation 1350 feet by the end of February. The fall drawdown and winter refill of Fort Randall reservoir is designed to increase winter hydropower generation at Oahe and Big Bend dams. 

Big Bend Dam releases averaged 19,600 cfs during January. They are expected to average 19,700 cfs this month. The reservoir will remain near its normal elevation of 1420 feet.  

Oahe Dam releases averaged 21,500 cfs during January. Releases are expected to average 18,900 cfs this month. The reservoir ended January at elevation 1607.2 feet, down 0.2 feet during the month. The reservoir is expected to rise less than 1.0 foot during February. 

Garrison Dam releases were gradually increased from 16,000 cfs to 23,000 cfs in January, averaging 19,600 cfs for the month. Releases are expected to remain at 23,000 cfs during February. The reservoir ended the month at 1839.3 feet, down 1.1 feet from the previous month and is expected to fall approximately 2 feet in February. 

Fort Peck Dam releases were increased from 6,000 cfs to 6,500 cfs in early January and averaged 6,200 cfs for the month. Releases were increased to 7,000 cfs in early February. The reservoir ended the month at elevation 2234.2 feet, up 0.7 feet from the previous month. The reservoir is expected to rise less than 1.0 foot in February. 

The forecast reservoir releases and elevations discussed above are not definitive. Adjustments to the reservoir release rates will be made as necessary to respond to actual conditions on the ground. 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. 

The six mainstem power plants generated 681 million kilowatt hours (kWh) of electricity in January. Average power generation in January is 712 million kWh. Projected 2015 generation is 9.6 billion kWh of electricity, compared to the normal of 10 billion kWh.  
 

MISSOURI RIVER MAIN STEM RESERVOIR DATA

WATER RELEASES AND ENERGY GENERATION FOR JANUARY