News Releases

Missouri River Basin drought conditions persist

Missouri River Water Management
Published Aug. 3, 2023
A graphic showing the base of the flood control pool for each of the six mainstem reservoirs and their distance from the mouth of the Missouri River at St. Louis. Additionally, the graphic shows the end of July pool elevations at the four largest reservoirs.

Missouri River Monthly Update for August. We break down the elements of runoff. After the plains snowmelt and mountain snowmelt, runoff forecasts to soil saturation and rainfall. Reservoir inflows in July have been declining due to the warmer and drier conditions in the upper Missouri River basin. After peaking in late July, System storage is expected to continue to decline into the Carryover Multiple Use Zone during the remainder of 2023 as we make releases during the summer and fall periods to meet the authorized purposes. John Remus, Chief Missouri River Basin Water Management Division

Two tables the first showing Missouri River Mainstem Reservoir Data with the Pool Elevation at the end of the month and how much the elevation has changed during the month and how much water is in storage at the end of the month compared to the average and how much the amount of water in storage has changed in May. 

The second table shows water releases and energy generation in May at each reservoir. There are three columns of data Average releases in 1000 cubic feet per second, volume of releases in acre feet, and how much power was generated from releases at each project. The data is provided in the photo caption.

MISSOURI RIVER MAINSTEM RESERVOIR DATA Pool Elevation (feet above mean sea level) On July 31 Change in July Water in Storage (1,000 acre-feet) On July 31 % of 1967-2022 Average Change in July Fort Peck 2230.4 -0.2 14,037 97 -50 Garrison 1842.4 +2.8 19,317 109 +915 Oahe 1603.7 -0.5 17,531 99 -115 Big Bend 1420.8 +0.1 1,675 98 +6 Fort Randall \1355.0 -1.0 3,408 102 -77 Gavins Point 1206.5 -0.3 339 87 -6 Water in Storage (1,000 acre-feet) On July 31 % of 1967-2022 Average Change in July Total 56,307 102 +673 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 8.8 543 88 Garrison 21.8 1,343 213 Oahe 25.7 1,577 240 Big Bend 25.4 1,561 85 Fort Randall 26.6 1,634 171 Gavins Point 29.0 1,783 80 Generation in Million kWh Total 877

July runoff in the Missouri River basin above Sioux City, Iowa was 3.3 million acre-feet (MAF), 99% of average.  Runoff was near or above average in all reaches except the Fort Peck reach, which was 68% of average.  

“Soil moisture conditions deteriorated in Montana, North Dakota, and northern South Dakota over the last month and improved across southern South Dakota and into the lower basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. 

Precipitation was below normal over most of the upper Missouri River basin last month except for small areas in Wyoming and southern South Dakota.  The lower basin saw a mix of above- and below-normal precipitation. 

The annual runoff forecast above Sioux City, Iowa is 28.5 MAF, 111% of average.

System storage peaked on July 22 at 56.6 MAF.  System storage on August 1 was 56.3 MAF, 0.2 MAF above the base of the Annual Flood Control and Multiple Use zone. 

“Reservoir inflows in July declined due to warmer and drier conditions in the upper Missouri River basin.  After peaking in late July, System storage is expected to continue declining into the Carryover Multiple Use Zone during the remainder of 2023 as we make releases during the summer and fall periods to meet the authorized purposes,” said Remus. 

“The monthly study indicates that the winter release from Gavins Point, which is based on the Sept. 1 System storage check, will likely be near the minimum rate of 12,000 cfs,” added Remus.

Basin and river conditions continue to be monitored and System regulation will be adjusted based on the most up-to-date information. 

Navigation:

Per the July 1 System storage check, navigation flow support was increased to 1,500 cfs below the full-service level. The flow support season length will be a full 8-month season, ending December 1 at the mouth of the Missouri River.   Gavins Point Dam releases are currently 31,500 cfs.  Releases will be set to provide flow support at the intermediate-service level at all four target locations (Sioux City, Omaha, Nebraska City, and Kansas City).

Reservoir Forecasts:

  • Gavins Point Dam
    • Average releases past month – 29,000 cfs
    • Current release rate – 31,500 cfs
    • Forecast release rate – 33,000 cfs
    • End-of-July reservoir level – 1206.5 feet
    • Forecast end-of-August reservoir level – 1206.5 feet
    • Notes: The Gavins Point release will be adjusted to provide navigation flow support on the lower Missouri River.
       
  • Fort Randall Dam
    • Average releases past month – 26,600 cfs
    • End-of-July reservoir level – 1355.0 feet
    • Forecast end-of-August reservoir level – 1355.2 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 – 25,400 cfs
    • Forecast average release rate – 31,800 cfs
    • Forecast end-of-August reservoir level – 1420.5 feet
       
  • Oahe Dam
    • Average releases past month – 25,700 cfs
    • Forecast average release rate – 32,000 cfs
    • End-of-July reservoir level – 1603.7 feet (down 0.5 feet from June 30)
    • Forecast end-of-August reservoir level – 1601.5 feet
       
  • Garrison Dam
    • Average releases past month – 21,800 cfs
    • Current release rate – 22,000 cfs
    • Forecast release rate – 22,000 cfs
    • End-of-July reservoir level – 1842.4 feet (up 2.8 feet from June 30)
    • Forecast end-of-August reservoir level – 1841.7 feet
    • Notes – Releases will be maintained at 22,000 cfs through mid-September.
       
  • Fort Peck Dam
    • Average releases past month – 8,800 cfs
    • Current release rate – 9,000 cfs
    • Forecast average release rate – 7,500 cfs
    • End-of-July reservoir level – 2230.4 feet (down 0.2 feet from June 30)
    • Forecast end-of-August reservoir level – 2229.0 feet
    • Notes: Releases will be maintained at 7,500 cfs through September.

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 877 million kWh of electricity in July. Typical energy generation for July is 956 million kWh. The power plants are expected to generate 7.8 billion kWh 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 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 1967-2022 Average

Change in July

Fort Peck

2230.4

-0.2

14,037

97

-50

Garrison

1842.4

+2.8

19,317

109

+915

Oahe

1603.7

-0.5

17,531

99

-115

Big Bend

1420.8

+0.1

1,675

98

+6

Fort Randall

1355.0

-1.0

3,408

102

-77

Gavins Point

1206.5

-0.3

339

87

-6

 

 

Total

56,307

102

+673

 

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

8.8

543

88

Garrison

21.8

1,343

213

Oahe

25.7

1,577

240

Big Bend

25.4

1,561

85

Fort Randall

26.6

1,634

171

Gavins Point

29.0

1,783

80

 

 

Total

877


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

Release no. 23-013