All 2017 stored flood waters were evacuated from the Missouri River mainstem reservoir system as of January 15, when the total volume stored in the System reached 56.1 million acre-feet, according to the U.S. Army Corps of Engineers Missouri River Water Management Division. “The System stands ready to capture spring runoff, reducing flood risk while providing support to other authorized project purposes,” said John Remus, Chief of the Missouri River Basin Water Management Division.

Over the last few weeks, periods of intermittent warming have caused some of the plains snowpack to melt and enter the System,” said Remus. System storage is currently 56.3 MAF. The latest annual runoff forecast for the Missouri River basin above Sioux City, Iowa, is 26.4 MAF, 104 percent of average. “While the forecasted annual runoff is near average, the timing and distribution of runoff in individual reaches varies. Runoff in the reaches between Garrison and Gavins Point is expected to be below normal during February through April, the months when plains snowpack normally melts. Runoff into Fort Peck and Garrison is expected to be slightly above average during May through July due to the above average mountain snowpack.”

Plains snowpack in the upper basin has been widespread, but light, so far this winter. Currently, some areas in central and eastern Montana are reporting 1-3 inches of liquid content while isolated areas in northeast Nebraska are reporting 1-2 inches of liquid content in the snowpack. However, there is light to no snow cover throughout the remainder of the upper and lower basin. The Corps is cooperating with other agencies to acquire plains snow measurements in the upper basin.

As of February 1, the mountain snowpack was 114 percent of average in the reach above Fort Peck and 124 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: https://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf.

Winter releases from Gavins Point are expected to remain at 18,000 cubic feet per second (cfs) during February, 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 2018 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 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. Weekly updates on basin conditions, reservoir levels and other topics of interest can be viewed here: https://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/weeklyupdate.pdf.

The USACE will continue to monitor basin conditions, including plains and mountain snow accumulation, and will adjust the regulation of the System based on the most up-to-date information.

Monthly Water Management Conference Calls

The Corps will host its second monthly conference call of 2018 on Tuesday, February 6, to inform basin stakeholders on current weather and runoff forecasts and the planned operation of the System. Presentation materials will be posted on the MRBWM website at: https://www.nwd-mr.usace.army.mil/rcc/. 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 www.dvidshub.net/unit/usace-nwd.

Reservoir Forecasts

• Gavins Point Dam releases averaged 20,700 cfs during January. Releases are expected to average near 18,000 cfs during the remainder of the winter but will be adjusted as necessary based on runoff and downstream river conditions. The Gavins Point reservoir ended January at elevation 1206.9 feet and will be drawn down to near 1206.0 feet during February.
• Fort Randall Dam releases averaged 18,600 cfs in January. Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point. The reservoir ended January at elevation 1347.8 feet rising 9.0 feet during the month. The reservoir will continue to rise to near 1351.5 feet during February to provide increased winter hydropower generation at Oahe and Big Bend.
• Big Bend Dam releases averaged 23,100 cfs in January. Releases are expected to average 18,200 cfs this month. The reservoir will remain near its normal elevation of 1420.0 feet during February.
• Oahe Dam releases averaged 24,600 cfs during January. Releases are expected to average 17,800 cfs in February. The reservoir ended January at elevation 1606.3 feet, falling 0.3 foot during the month. The reservoir level is expected to rise approximately 1.3 feet during February.
• Garrison Dam releases were gradually increased from 20,000 to 25,000 cfs averaging 24,200 cfs for the month. Releases will be held near 25,000 cfs during February. Garrison reservoir ended January at elevation 1839.1 feet, declining 1.5 feet during the month. The reservoir level is expected to decline 1.2 feet during February, ending the month near elevation 1837.9 feet.
• Fort Peck Dam releases averaged 9,900 cfs during January and will be near 10,500 cfs during February. The reservoir ended January at elevation 2234.9 feet, declining 0.9 foot during the month. The reservoir is expected to fall approximately 0.5 foot during February ending the month 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 807 million kWh of electricity in January. Typical energy generation for January is 708 million kWh. The power plants are projected to generate 10.0 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 https://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf.

MISSOURI RIVER MAINSTEM RESERVOIR DATA

WATER RELEASES AND ENERGY GENERATION FOR JANUARY