US Army Corps of Engineers
Northwestern Division

News Releases

Reservoir system prepared for 2019 runoff season

Published Feb. 7, 2019
Missouri River Water Management Monthly Update - Each month, from January through the end of the runoff season, Missouri River water managers and weather forecasters report the conditions of the Missouri River Basin.

Missouri River Water Management Monthly Update - Each month, from January through the end of the runoff season, Missouri River water managers and weather forecasters report the conditions of the Missouri River Basin.

Missouri River Basin - Weekly Update - Feb. 5, 2019

System storage reached 56.1 MAF, the base of the Annual Flood Control and Multiple Use Zone, on January 28, 2019. This means that all stored flood waters from 2018 have been evacuated. The upper Basin runoff forecast for 2019 is 25.6 MAF, which is about average. Mountain snowpack is currently below average (lower right graphic). Plains snow conditions vary throughout the upper Basin: light in Montana and North Dakota, and moderate-to-heavy in the central and eastern Dakotas (upper right graphic). The Gavins Point winter release is currently 20,000 cfs. Releases are expected to be reduced to 17,000 cfsby mid-February. Ice conditions will be closely monitored.

Mountain snowpack is currently below average. At this time last year, it was 124 percent to 134 percent above average.

Mountain snowpack is currently below average. At this time last year, it was 124 percent to 134 percent above average.

OMAHA, NE – All 2018 stored flood waters were evacuated from the Missouri River mainstem reservoir system (System) as of Jan. 29. The full 16.3 million acre-feet (MAF) of designated flood control storage is available to manage 2019 runoff. “The System stands ready to capture spring runoff, reducing flood risk while providing support to other authorized project purposes. Current Gavins Point releases are 20,000 cubic feet per second (cfs) and will be decreased to 17,000 cfs by mid-February,” said John Remus, Chief of the Corps’ Missouri River Basin Water Management Division.

The latest annual runoff forecast for the Missouri River basin above Sioux City, Iowa is 25.6 MAF, slightly more than the long-term average of 25.3 MAF. Runoff into Fort Peck and Garrison is expected to be below average over the next few months due to the lighter-than-average plains snowpack and below-average mountain snowpack. Runoff in the Sioux City reach is expected to be above average over the next few months as the northern portions of the James River and Big Sioux River basins have widespread and moderate-to-heavy plains snowpack. Portions of those basins contain 4 to 5 inches of estimated liquid content in the snowpack. The remainder of the upper and lower Missouri River basin has light to no snow cover. The Corps is cooperating with other agencies to acquire plains snow measurements in the upper basin.
As of Feb. 4, the mountain snowpack was 88 percent of average in the reach above Fort Peck and 89 percent of average in the reach from Fort Peck to Garrison. Normally, by Feb. 1, 64 percent of the total mountain snowpack accumulation has occurred. 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.

Current studies indicate flow support for Missouri River navigation will be at full service levels for the first half of the 2019 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 the guidelines in the Master Manual. Flow support for the second half of the navigation season, as well as navigation season length, will be based on the actual July 1 System storage.

River ice conditions below all System projects will be closely monitored throughout the winter season. The Corps will also continue to monitor basin and river conditions, including plains and mountain snow accumulation, and will adjust System regulation based on the most up-to-date information.

Weekly updates on basin conditions, reservoir levels and other topics of interest can be viewed here: http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/weeklyupdate.pdf.

Reservoir Forecasts
Gavins Point Dam

  • Average releases past month – 23,100 cfs
  • Current release rate – 20,000 cfs
  • Forecast release rate – 17,000 cfs by mid-February
  • End-of-January reservoir level – 1204.2 feet
  • Forecast end-of-February reservoir level – 1206.0 feet
  • Notes: Due to scheduled maintenance on the hydropower units, releases may be made from both the powerhouse and spillway.

Fort Randall Dam

  • Average releases past month – 20,700 cfs
  • End-of-January reservoir level – 1344.7 feet (up 4.2 feet from December)
  • Forecast end-of-February reservoir level – 1350.0 feet
  • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point. Gradually refilled the reservoir to 1350.0 feet allows increased winter hydropower generation at Oahe and Big Bend.

Big Bend Dam

  • Average releases past month – 23,100 cfs
  • Forecast average release rate –22,300 cfs
  • Forecast reservoir level – 1420.0 feet

Oahe Dam

  • Average releases past month – 24,900 cfs
  • Forecast average release rate – 22,000 cfs
  • End-of-January reservoir level – 1605.9 feet (down 1.3 feet from December)
  • Forecast end-of-February reservoir level – 1606.7 feet
  • Notes: River ice conditions continue to be monitored below the dam and releases will be adjusted accordingly to minimize flood risk caused by river ice.

Garrison Dam

  • Average releases past month – 20,200 cfs (ranging from 16,000 cfs to 26,000 cfs)
  • Current release rate – 26,000 cfs
  • Forecast average release rate – 26,000 cfs
  • End-of-January reservoir level – 1838.9 feet (down 0.7 feet from December)
  • Forecast end-of-February reservoir level – 1837.5 feet
  • Notes: River ice conditions continue to be monitored below the dam and releases will be adjusted accordingly to minimize flood risk caused by river ice.

Fort Peck Dam

  • Average releases past month – 11,800 cfs
  • Forecast average release rate – 12,000 cfs
  • End-of-January reservoir level – 2235.8 feet (down 1.4 feet from December)
  • Forecast end-of-February reservoir level – 2234.7 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 804 million kWh of electricity in January. Typical energy generation for January is 708 million kWh. The power plants are projected to generate 9.7 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

 

Pool Elevation
(feet above mean sea level)

Water in Storage
(1,000 acre-feet)

 

On January 31

Change in January

On January 31

% of 1967-2018 Average

Change in January

Fort Peck

2235.8

-1.4

15,172

105

-313

Garrison

1838.9

-0.7

18,155

102

-256

Oahe

1605.9

-1.3

18,158

103

-409

Big Bend

1420.3

-0.4

1,645

96

-26

Fort Randall

1344.7

+4.2

2,620

78

+259

Gavins Point

1204.3

-1.4

290

74

-30

 

 

Total

56,040

101

-775

 

WATER RELEASES AND ENERGY GENERATION FOR JANUARY

 

Average Release in 1,000 cfs

Releases in 1,000 acre-feet

Generation in Million kWh

Fort Peck

11.8

726

121

Garrison

20.2

1,240

188

Oahe

24.9

1,528

226

Big Bend

23.1

1,420

87

Fort Randall

20.7

1,274

124

Gavins Point

23.1

1,422

57

 

 

Total

803


Contact
Eileen Williamson
402-996-3802
eileen.l.williamson@usace.army.mil

Release no. 19-003