News Releases

Reservoir system prepared for 2017 runoff season; Missouri Basin runoff near average for 2016

Missouri River Water Management Division
Published Jan. 9, 2017
The Missouri River Water Management office releases a report at the beginning of each month to the public documenting the monthly river forecast and release schedule. The Missouri River Water Management Division is part of the Northwestern Division of the U.S. Army Corps of Engineers and is located in Omaha, Nebraska.

The Missouri River Water Management office releases a report at the beginning of each month to the public documenting the monthly river forecast and release schedule. The Missouri River Water Management Division is part of the Northwestern Division of the U.S. Army Corps of Engineers and is located in Omaha, Nebraska.

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 water was evacuated from the reservoir system as of December 18, when the total volume stored in the Mainstem Reservoir System reached 56.1 million acre-feet (MAF). “Due to the complete evacuation of the reservoir system, Gavins Point releases were reduced from 18,000 cubic feet per second (cfs) to the normal winter rate of 17,000 cfs on January 5. Basin conditions will continue to be monitored and reservoir releases adjusted as needed throughout the winter in preparation for the 2017 runoff season”, said Jody Farhat, Chief of the Missouri River Water Management Division. “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.”

Runoff in the Missouri River Basin above Sioux City, Iowa, was 0.9 MAF during December, 114 percent of average. December’s runoff resulted in a 2016 calendar year runoff total of 24.2 MAF, 96 percent of average, according to the Corps. Average annual runoff is 25.3 MAF.

The upper plains, particularly in North Dakota and northern South Dakota, experienced heavy snowfall during December. Some areas in central North Dakota are reporting as much as 3-4 inches of water content from current snowpack. The surrounding areas of eastern Montana and western and northern South Dakota have accumulated 1-3 inches of water 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 Jan. 9, the mountain snowpack was 78 percent of average in the reach above Fort Peck and 104 percent of average in the reach from Fort Peck to Garrison. Normally 44% of the total mountain snowpack accumulation has occurred by Jan. 1. Mountain snowpack will continue to accumulate overthe 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.

Based on the current soil moisture and mountain and plains snowpack conditions, 2017 runoff in the Missouri River Basin above Sioux City, Iowa, is forecast to be 25.4 MAF, 100 percent of average. Timing and distribution of the forecasted runoff, however, varies widely based on the snowpack data discussed above.

Winter releases from Gavins Point will be at least 17,000 cfs based on the September 1 system storage check, 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.

With increased chances of below average temperatures in the upper basin for the remainder of winter, ice conditions and river stages will be closely monitored throughout the basin. The Corps will make reservoir release adjustments as necessary to lessen the impact of river ice formation based on conditions below Garrison, Oahe and Gavins Point dams. Releases from Garrison are forecast to remain at 16,000 cfs during January to reduce the risk of ice-induced flooding in the Bismarck area and to help balance storage in the upper three reservoirs. Minimum releases will be specified at Oahe during extreme cold periods to reduce the risk of ice-induced flooding in the Pierre area.

Final 2016-2017 Annual Operating Plan Released
After reviewing comments received on the draft, the Missouri River Basin Water Management Division developed and released the Final Annual Operating Plan for the Missouri River Basin for 2016–2017. The plan is posted at https://www.nwd.usace.army.mil/MRWM/Public-Meetings/.

Monthly Water Management Conference Calls Begin for 2017
The Corps will host its first conference call of 2017 on Monday, January 9, 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.nwd.usace.army.mil/MRWM/Public-Meetings/.

Reservoir Forecasts
Gavins Point Dam releases averaged 18,000 cfs during December. Releases were stepped down to 17,000 cfs in early January. The Gavins Point reservoir ended December at elevation 1207.9 feet and will remain near elevation 1207.5 feet during January.

Fort Randall Dam releases averaged 16,300 cfs in December. Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point Dam. The reservoir ended December at elevation 1340.9 feet, rising 2.1 feet during the month. The reservoir will continue to gradually rise, ending January near 1345.0 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 16,900 cfs in December. Releases are expected to average 19,200 cfs this month. The reservoir will remain near its normal elevation of 1420.0 feet during January.

Oahe Dam releases averaged 18,300 cfs during December. Releases are expected to average 18,600 cfs in January. The reservoir ended December at elevation 1608.4 feet, falling 0.6 feet during the month. The reservoir level is expected to fall slightly during January, ending the month near elevation 1608.0 feet.

Garrison Dam releases averaged 15,700 cfs during the month of December. Releases are forecasted to remain near 16,000 cfs through January. Garrison reservoir ended December at elevation 1838.1 feet, falling 1.3 feet during the month. The reservoir level is expected to fall during January, ending the month near elevation 1837.2 feet.

Fort Peck Dam releases averaged 6,500 cfs during December and are forecasted to remain near 7,000 during January. The reservoir ended December at elevation 2234.2 feet, falling 0.7 feet during the month. The reservoir is expected to end January near elevation 2233.6 feet.

The forecasted 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 595 million kWh of electricity in December. Typical energy generation for December is 684 million kWh. The 2016 total power generation was 7.6 billion kWh. The power plants are projected to generate 9.2 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

 

Pool Elevation

(feet above mean sea level)

Water in Storage

(1,000 acre-feet)

 

On December 31

Change in December

On December 31

% of 1967-2015 Average

Change in December

Fort Peck

2234.2

-0.7

14,828

105

-161

Garrison

1838.1

-1.3

17,934

104

-407

Oahe

1608.4

-0.6

18,962

114

-184

Big Bend

1420.7

-0.1

1,670

98

-6

Fort Randall

1340.9

+2.1

2,382

92

+118

Gavins Point

1207.9

-0.1

372

91

-2

 

 

Total

56,148

106

-642

 

WATER RELEASES AND ENERGY GENERATION FOR DECEMBER

 

Average Release

(1,000 cfs)

Releases

(1,000 acre-feet)

Generation

(Million kWh)

Fort Peck

6.5

398

67

Garrison

15.7

965

149

Oahe

18.3

1,128

170

Big Bend

16.9

1,041

65

Fort Randall

16.3

1,004

92

Gavins Point

18.0

1,107

52

 

 

Total

595


Contact
Amy Gaskill
503-808-3710
amy.j.gaskill@usace.army.mil

Release no. 17-001