US Army Corps of Engineers
Northwestern Division Website

News Releases

Drought conditions persist in the upper Missouri River Basin

Missouri River Water Management Division
Published Aug. 5, 2021
The six dams on the main stem of the Missouri River capture runoff from parts of Montana, North Dakota, South Dakota, Wyoming, and northern Nebraska.

The six dams on the main stem of the Missouri River capture runoff from parts of Montana, North Dakota, South Dakota, Wyoming, and northern Nebraska.

Runoff can enter the Missouri River anywhere and anytime in the basin. Only when runoff occurs in the upper Missouri River basin can it be captured by the mainstem system of dams. Even then, where runoff is captured depends upon where precipitation falls.

Runoff can enter the Missouri River anywhere and anytime in the basin. Only when runoff occurs in the upper Missouri River basin can it be captured by the mainstem system of dams. Even then, where runoff is captured depends upon where precipitation falls.

Drought conditions continue to impact the upper Missouri River Basin above Sioux City, Iowa (upper Basin). July runoff in the upper Basin was 34% of average. July runoff above Fort Peck Dam was the lowest in 123 years of record-keeping.

The updated 2021 upper Basin runoff forecast is 14.6 million acre-feet (MAF), 57% of average. If realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on August 1 was 53.9 MAF, 2.2 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.

“Reservoir inflows in July have been declining due to the warmer and drier conditions in the upper Basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “Per the July 1 System storage check, navigation support will be maintained at an intermediate service level, 1,500 cubic feet per second (cfs) below full-service levels, through the end of the normal 8-month navigation flow support season, which will end on Dec. 1 at the mouth,” added Remus.

USACE will evaluate lower Missouri River flow conditions to set Gavins Point releases to ensure that flows at the four downstream navigation target locations will be at or above the intermediate service level. The monthly study also indicates that the winter release from Gavins Point, which is based on the September 1 System storage check, will likely be at a minimum rate of 12,000 cfs.

Fall public meetings are currently scheduled to be held October 25-28 at several locations along the Missouri River. Locations and details will be included in the September update.

Drought Conditions:

Soil conditions in the upper basin are very dry. Drought conditions throughout the entire Basin, particularly in the upper basin, worsened in July. According to the National Drought Mitigation Center, approximately 75% of the Missouri River basin is currently experiencing some form of abnormally dry or drought conditions, an increase of 10% since the end of June. The seasonal drought outlook, which extends through the end of September, shows drought conditions will persist or expand across the upper basin. Drought information can be viewed at:  https://droughtmonitor.unl.edu/.

Navigation:

Gavins Point Dam releases will be set to provide flow support at an intermediate service level, 1,500 cfs less than full service flow support at all four target locations (Sioux City, Omaha, Nebraska City, and Kansas City). Flow support for the second half of the navigation season, as well as the navigation season length, are based on July 1 System storage. The flow support season length will be a full 8-month season, ending Dec. 1 at the mouth of the Missouri River.

Mountain Snowpack:

Mountain snowpack in the upper Basin melted out in mid- to late-June, several weeks earlier than normal. The mountain snowpack peaked above Fort Peck in late March at 86% of average, while the mountain snowpack in the Fort Peck to Garrison reach peaked in late April at 96% of average. Mountain snowpack normally peaks near April 15. The mountain snowpack graphics can be viewed at: http://go.usa.gov/xARQC.

Winter Release Rate:

The winter release rate is determined based on the September 1 System storage. Per the July 1 reservoir studies, the winter releases from Gavins Point Dam will likely be at the minimum rate of 12,000 cfs.

Monthly Water Management Conference Calls

Water management calls include an update from the National Weather Service’s Missouri Basin River Forecast Center, and an update on the Missouri River mainstem reservoir system operations. The next call for 2021 will be held on Thursday, August 5. All calls are recorded in their entirety and are available to the public on our website at https://go.usa.gov/xARQv.

Reservoir Forecasts:

  • Gavins Point Dam
    • Average releases past month – 29,100 cfs
    • Current release rate – 31,000 cfs
    • Forecast release rate – 31,500 cfs
    • End-of-July reservoir level – 1206.2 feet
    • Forecast end-of-August reservoir level – 1206.5 feet
    • Notes: The Gavins Point release will be adjusted to provide intermediate-service navigation flow support on the lower Missouri River through December 1, the second half of the navigation season.
       
  • Fort Randall Dam
    • Average releases past month – 27,200 cfs
    • End-of-July reservoir level – 1355.1 feet
    • Forecast end-of-August reservoir level – 1355.0 feet
    • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point and to back up Gavins Point releases.
       
  • Big Bend Dam
    • Average releases past month – 27,600 cfs
    • Forecast average release rate – 30,100 cfs
    • Forecast reservoir level – 1420.7 feet
       
  • Oahe Dam
    • Average releases past month – 27,900 cfs
    • Forecast average release rate – 30,600 cfs
    • End-of-July reservoir level – 1603.4 feet (down 1.5 foot from July 1)
    • Forecast end-of-August reservoir level – 1601.1 feet
       
  • Garrison Dam
    • Average releases past month – 22,000 cfs
    • Current release rate – 22,000 cfs
    • Forecast release rate – 21,000 cfs
    • End-of-July reservoir level – 1834.7 feet (down 1.8 feet from July 1)
    • Forecast end-of-August reservoir level – 1832.6 feet
    • Notes – Releases will be maintained at 22,000 cfs through August.
       
  • Fort Peck Dam
    • Average releases past month – 9,400 cfs
    • Current release rate – 9,500 cfs
    • Forecast average release rate – 9,500 cfs
    • End-of-July reservoir level – 2230.8 feet (down 1.7 foot from July 1)
    • Forecast end-of-August reservoir level – 2228.8 feet
    • Notes: Releases will be maintained at 9,500 cfs through August.

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.

Hydropower:

The six mainstem power plants generated 878 million kWh of electricity in July. Typical energy generation for July is 961 million kWh. The power plants are expected to generate 8.7 billion kWh this year, compared to the long-term average of 9.5 billion kWh.

To view the detailed three-week release forecast for the mainstem dams, go to https://go.usa.gov/xARQB.

The Missouri Basin Web App provides links to these reports and others that are updated more frequently. http://go.usa.gov/xE6fC

 

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 1967-2020 Average

Change in July

Fort Peck

2230.8

-1.7

14,121

97

-363

Garrison

1834.7

-1.8

16,911

95

-541

Oahe

1603.4

-1.5

17,425

98

-442

Big Bend

1420.7

-0.1

1,668

98

-12

Fort Randall

1355.1

+0.4

3,415

102

+35

Gavins Point

1206.2

-0.2

333

85

-4

 

 

Total

53,873

97

-1,327

 

WATER RELEASES AND ENERGY GENERATION FOR JUNE

 

Average Release in 1,000 cfs

Releases in 1,000 acre-feet

Generation in Million kWh

Fort Peck

9.4

578

95

Garrison

22.0

1,355

207

Oahe

27.9

1,714

258

Big Bend

27.6

1,699

92

Fort Randall

27.2

1,674

175

Gavins Point

29.2

1,796

50

 

 

Total

877


Contact
Eileen Williamson
4102-996-3802
eileen.l.williamson@usace.army.mil

Release no. 21-046