OMAHA, Neb. – The full flood control capacity of the Missouri River mainstem reservoir system is available for the 2017 runoff season, according to the U.S Army Corps of Engineers (Corps) Missouri River Water Management Division. All 2016 stored flood waters were evacuated as of December 18, when the total volume stored in the reservoir system reached 56.1 million acre-feet (MAF). “The entire flood control capacity of the Mainstem Reservoir System stands ready to capture spring runoff, reducing flood risk while providing support to other authorized project purposes,” said Jody Farhat, Chief of the Missouri River Basin Water Management Division.

Heavy snowfall occurred this winter throughout the upper plains, particularly in North Dakota and northern South Dakota. Some areas in central North Dakota are reporting as much as 3-5 inches of liquid content in the current snowpack with small pockets indicating higher amounts. The surrounding areas of eastern Montana and central South Dakota have accumulated 1-3 inches of liquid content in the plains snowpack, while the remainder of the upper plains and the lower basin have little plains snow accumulation. The Corps is cooperating with other agencies to acquire plains snow measurements in the upper basin.

As of February 1, the mountain snowpack was 75 percent of average in the reach above Fort Peck and 106 percent of average in the reach from Fort Peck to Garrison. Normally 64 percent of the total mountain snowpack accumulation has occurred by February 1. Mountain snowpack will continue to accumulate over the next few months and normally peaks in mid-April. View mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf.

The latest annual runoff forecast for the Missouri River basin above Sioux City, Iowa, is 26.2 MAF, 103 percent of average. “While the annual runoff is near average, the timing and distribution of runoff in individual reaches varies. Runoff in the reach between Garrison and Oahe is expected to be above normal in February through April, the months when plains snowpack normally melts,” said Farhat. “Runoff into Fort Peck is expected to be below normal in the late spring due to the lower than average mountain snowpack in that reach.”

“In preparation of the plains snowmelt, releases at Fort Peck and Garrison have been reduced to help evacuate the last half-foot of water in the annual flood control pool at Oahe,” said Farhat. Weekly updates on plains and mountain snowpack conditions, basin/runoff status, and current reservoir levels can be viewed here: http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/weeklyupdate.pdf.

Winter releases from Gavins Point are expected to remain at 17,000 cubic feet per second (cfs), but will be adjusted if needed in response to basin conditions. Flow support for Missouri River navigation will likely be at full service levels for the first half of the 2017 season, which begins on April 1 at the mouth. The actual service level will be based on the total volume of water stored in the reservoir system on March 15, 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 based on the actual July 1 system storage.

The Corps will continue to monitor basin conditions, mountain snow and plains snow accumulation, and adjust operations accordingly.

Monthly Water Management Conference Calls

The Corps will host its second monthly conference call of 2017 on Monday, February 6, to inform basin stakeholders on current weather and runoff forecasts and the planned operation of the reservoir system in the coming months. Presentation materials will be available via webinar. The call is intended for Congressional delegations; Tribes; state, county and local government officials; and the media. It will be recorded in its entirety and made available to the public on the Defense Video and Imagery Distribution System at https://www.dvidshub.net/unit/usace-nwd.

Reservoir Forecasts

Gavins Point Dam releases averaged 17,100 cfs during January and will remain near 17,000 cfs during February. The Gavins Point reservoir ended January at elevation 1207.8 feet and will gradually be lowered to 1206.0 feet during February.

Fort Randall Dam releases averaged 14,900 cfs in January. Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point Dam. The reservoir ended January at elevation 1346.0 feet, rising 5.1 feet during the month.  The reservoir will continue to gradually rise, ending February near 1352.0 feet. The reservoir is normally refilled during the winter to provide extra winter hydropower generation at Oahe and Big Bend Dams.

Big Bend Dam releases averaged 17,000 cfs in January. Releases are expected to average 19,900 cfs this month.  The reservoir will remain near its normal elevation of 1420.0 feet during February.

Oahe Dam releases averaged 18,700 cfs during January. Releases are expected to average 19,100 cfs in February. The reservoir ended January at elevation 1607.9 feet, falling 0.5 feet during the month. The reservoir level is expected to fall slightly during February, ending the month near elevation 1607.4 feet.

Garrison Dam releases averaged 15,900 cfs during the month of January. Releases were gradually reduced from 16,000 cfs in late January to 13,000 cfs in early February. Releases will remain at that rate during February. Garrison reservoir ended January at elevation 1837.5 feet, falling 0.6 feet during the month. The reservoir level is expected to remain nearly steady during February, ending the month near elevation 1837.6 feet.

Fort Peck Dam releases averaged 6,700 cfs during January. Releases were reduced to 4,500 cfs in early February and will remain at that rate through the month. The reservoir ended January at elevation 2233.9 feet, falling 0.3 feet during the month. The reservoir is expected to rise slightly, ending February near elevation 2234.4 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 594 million kWh of electricity in January. Typical energy generation for January is 708 million kWh. The power plants are projected to generate 9.1 billion kWh of electricity this year, compared to the long-term average of 9.3 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.

MISSOURI RIVER MAINSTEM RESERVOIR DATA

WATER RELEASES AND ENERGY GENERATION FOR JANUARY