US Army Corps of Engineers
Northwestern Division

News Releases

System storage has peaked; Gavins Point releases to remain at high levels into fall

Northwestern Division
Published Aug. 6, 2019
System storage is 67.7 MAF; 11.6 MAF of the 16.3 MAF of flood control storage is occupied. About 29% of the flood control storage remains available to store runoff. System storage peaked at 68.5 MAF on July 20.

System storage is 67.7 MAF; 11.6 MAF of the 16.3 MAF of flood control storage is occupied. About 29% of the flood control storage remains available to store runoff. System storage peaked at 68.5 MAF on July 20. The NOAA observed precipitation for the past 7 days has been a mix of above and below normal in every Basin state, with some areas experiencing over 600 percent of normal precipitation (lower right graphic). The 2019 calendar year runoff forecast above Sioux City, updated on August 1, is 52.9 MAF (209% of average). If realized, this will be the 2nd highest runoff in 121 years of record-keeping, surpassed only by 2011. Gavins Point releases are currently 70,000 cfs. Refer to the 3-Week Forecast for the most up-to-date System information – pool levels, inflows and releases.

Widespread and heavy rainfall in the upper Missouri River basin (above Sioux City) resulted in another month of above average runoff. Areas of Montana, Wyoming, South Dakota, and Nebraska received two to three times normal precipitation during July.

July runoff in the upper basin was 7.0 million acre feet (MAF), which is 213% of average. The average July runoff is 3.3 MAF. Runoff remained particularly high in the reaches from Garrison Dam in North Dakota to Sioux City, Iowa, which ranged between three to seven times average. 

The 2019 upper basin runoff forecast is 52.9 MAF. If realized, this runoff total will be the second highest runoff in 121 years of record-keeping, only surpassed by 2011 (61.0 MAF) and exceeding 49.0 MAF observed in 1997. Total upper basin runoff through July 31 was 45.3 MAF, exceeding the total upper basin runoff in 2018 of 42.1 MAF. 

System releases from Gavins Point Dam are currently 70,000 cubic feet per second (CFS), which is nearly twice the average release for this time of the year.

“We will maintain Gavins Point releases at this rate to continue evacuating water from the Missouri River mainstem reservoir system (System),” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division.

System storage was 68.0 MAF as of August 1, occupying 11.9 MAF of the 16.3 MAF flood control zone. System storage, which normally peaks in early July, peaked at 68.5 MAF on July 20. Garrison is currently in its exclusive flood control zone while Fort Peck and Oahe are slightly below their respective exclusive flood control zones. As a result of the high reservoir levels and the forecast above-average runoff during the summer and fall, releases from all System projects will be above average for the next several months, and possibly as late as November, to ensure evacuation of all stored flood waters.

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.

Monthly Water Management Conference Calls

Due to the ongoing flooding in the lower basin,  weekly calls for key basin stakeholders, include a briefing from the National Weather Service’s Missouri Basin River Forecast Center, an update on the Missouri River mainstem reservoir system operations, and updates on the ongoing and planned flood recovery efforts in the Omaha and Kansas City Districts. The next call will be held Thursday, August 8. The call is intended for Congressional delegations; Tribes; state, county and local government officials, levee and drainage districts; 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
    • Average releases past month – 70,000 cfs
    • Current release rate – 70,000 cfs
    • Forecast release rate – 70,000 cfs
    • End-of-July reservoir level – 1206.6 feet
    • Forecast end-of-August reservoir level – 1206.6 feet
       
  • Fort Randall Dam
    • Average releases past month – 63,500 cfs
    • End-of-July reservoir level – 1361.3 feet (down 1.7 feet from June)
    • Forecast end-of-August reservoir level – 1356.1 feet
    • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point.
       
  • Big Bend Dam
    • Average releases past month – 51,900 cfs
    • Forecast average release rate – 56,300 cfs
    • Forecast reservoir level – 1420.0 feet
       
  • Oahe Dam
    • Average releases past month – 55,500 cfs
    • Forecast average release rate – 56,500 cfs
    • End-of-July reservoir level – 1617.0 feet (rising 0.3 foot during July)
    • Forecast end-of-August reservoir level – 1615.3 feet
       
  • Garrison Dam
    • Average releases past month – 46,400 cfs
    • Current release rate – 46,000 cfs
    • Forecast average release rate – 46,000 cfs
    • End-of-July reservoir level – 1851.7 feet (falling 0.2 foot during July)
    • Forecast end-of-August reservoir level – 1848.0 feet
       
  • Fort Peck Dam
    • Average releases past month – 12,900 cfs
    • Current release rate – 15,000 cfs
    • Forecast average release rate – 15,000 cfs
    • End-of-July reservoir level – 2246.2 feet (down 0.2 foot from June)
    • Forecast end-of-August reservoir level – 2244.0 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 1490 million kWh of electricity in July. Typical energy generation for July is 951 million kWh. The power plants are projected to generate 13.1 billion kWh of electricity this year, compared to the long-term average of 9.4 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 July 31

Change in July

On July 31

% of 1967-2018 Average

Change in July

Fort Peck

2246.2

-0.2

17,537

121

-48

Garrison

1851.6

-0.2

22,569

127

-48

Oahe

1616.9

+0.3

21,868

124

+207

Big Bend

1420.7

+0.4

1,674

98

+14

Fort Randall

1361.3

-1.7

3,966

119

-157

Gavins Point

1206.6

+0.3

342

87

+8

 

 

Total

67,956

123

-24

 

 

WATER RELEASES AND ENERGY GENERATION FOR JULY

 

Average Release in 1,000 cfs

Releases in 1,000 acre-feet

Generation in Million kWh

Fort Peck

12.9

792

121

Garrison

46.4

2,852

396

Oahe

55.5

3,413

530

Big Bend

51.9

3,193

160

Fort Randall

63.5

3,907

221

Gavins Point

70.0

4,304

62

 

 

Total

1,490


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

Release no. 19-054