News Releases

Despite early runoff, upper basin runoff forecast below average; Gavins Point releases to increase for navigation flow support

Missouri River Basin Water Management
Published March 7, 2024
Map of the Missouri Basin with the Mainstem Dams marked wih red pin drops and the downstream flow target locations marked with yellow arrows. The March 1 funoff forecast for the Misouri River Basin above Sioux City, Iowa is 17.0 Million Acre Feet which is 66% of average and down from 18.8 MAF in February

System Storage Checks: March and July system storage checks help determine the level of flow support for navigation and other downstream purposes as well as the navigation season length. March 15 - used to set service level for first half of the navigation season. July 1 - used to set service level for second half of navigation season and set season service length. September 1 - used to set the winter System release rate.

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 for the month. 

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.


Mountain Snow Graphic
The graphic is a split screen with a snowscape showing plains snow and mountain snow with snow in the clouds. and statements that say. Plains Snow - snowmelt is typically complete by mid-April. Snow Melt - the rate of snowmelt and how much becomes runoff can be impacted by rainfall, air temperatures, and soil moisture. Mountain Snow - begins to accumulate in October. Snowmelt is typically complete by July. Base Flows - river stages will be higher when the soil is saturated and lower when the soil is dry. The left side of the graphic is the Mountain snow accumulation - Mountain Snowpack Water Content 2022-2023 with comparison plots from recent high and low years. At the bottom right is the current forecast.

MISSOURI RIVER MAINSTEM RESERVOIR DATA Pool Elevation (feet above mean sea level) On February 29 Change in February Water in Storage (1,000 acre-feet) On February 29 % of 1967-2023 Average Change in February Fort Peck 2230.4 +1.0 14,035 97 +203 Garrison 1835.1 -1.8 17,030 96 -538 Oahe 1603.6 +3.6 17,486 99 +1,032 Big Bend 1420.6 -0.2 1,666 98 -9 Fort Randall 1352.1 +6.8 3,164 95 +506 Gavins Point 1206.6 -0.8 340 87 -20 Total 53,721 97 +1,174 WATER RELEASES AND ENERGY GENERATION FOR FEBRUARY Average Release in 1,000 cfs Releases in 1,000 acre-feet Generation in Million kWh Fort Peck 5.4 308 43 Garrison 24.9 1,430 214 Oahe 10.8 621 90 Big Bend 12.4 712 40 Fort Randall 7.1 407 43 Gavins Point 13.0 748 35 Total 465

A warm February led to increased snowmelt and runoff in the Missouri River Basin above Sioux City, Iowa. February runoff was 1.8 million acre-feet, 161% of average with above average runoff in every reach except Sioux City, which was near average. However, the updated 2024 calendar year runoff forecast for the basin continues to be below average.   

“Despite the increased runoff in the month of February, and improved soil moisture conditions, we expect 2024 runoff to remain below average,” said John Remus, chief of the U.S. Army Corps of Engineers’, Missouri River Basin Water Management Division.  “The much warmer-than-normal temperatures led to an early melt of the lower-than-average plains snow.  In addition, mountain snowpack is lower than average, resulting in the low annual runoff forecast.” Soil moisture conditions are near or above normal across most the basin with below-normal soil moisture conditions spanning eastern portions of the basin.

The 2024 calendar year runoff forecast above Sioux City is 17.0 MAF, 66% of average. The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack, and long-term precipitation and temperature outlooks. 

System storage is currently 53.9 MAF, 2.2 MAF below the top of the carryover multiple use zone. 

“The System will continue to serve all Congressionally authorized purposes during 2024,” said Remus.

Basin and river conditions continue to be monitored, including plains and mountain snow accumulation, and System regulation will be adjusted based on the most up-to-date information.

Navigation:

Beginning in mid-March, releases from Gavins Point Dam will be adjusted to provide flow support for Missouri River navigation.  Navigation flow support for the Missouri River is expected to be at 500 cubic feet-per-second below full service for the first half of the 2024 season, which begins April 1 at the mouth of the river near St. Louis, Missouri. The actual service level will be based on the total volume of water stored within 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 storage in the System on July 1.

Mountain and Plains Snowpack:

Mountain snowpack in the upper Missouri River Basin is accumulating at below average rates. The March 3, mountain snowpack in the Fort Peck reach was 73% of average, while the mountain snowpack in the Fort Peck to Garrison reach was 78% of average.  By March 1, about 80% of the total mountain snowfall has typically accumulated.  Mountain snow normally peaks near April 17. The mountain snowpack graphics can be viewed at: http://go.usa.gov/xARQC.  

The plains snowpack, which typically melts from mid-February into April, is almost nonexistent in the Basin.  Trace to 1” of snow water equivalent is modeled in eastern North Dakota.

Monthly Water Management Conference Calls for 2024:

The March 2024 monthly conference call will be held Thursday, March 7, to inform basin stakeholders of 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 our website at https://go.usa.gov/xARQv.

Spring Public Meetings:

The Northwestern Division, Missouri River Basin Water Management Division will host a series of public meetings the week of March 25.  Dates and locations are listed below.  Additional information, with specific times and venues, will be provided in a future news release and will also be posted to the website at:  https://www.nwd.usace.army.mil/MRWM/Public-Meetings/.

  • Tuesday, March 26 – Fort Yates, North Dakota
  • Wednesday, March 27 – Fort Pierre, South Dakota
  • Thursday, March 28 – Poplar, Montana

Reservoir Forecasts:

  • Gavins Point Dam
    • Average releases past month – 13,000 cfs
    • Current release rate – 13,000 cfs
    • Forecast release rate – 20,600 cfs
    • End-of-February reservoir level – 1206.6 feet
    • Forecast end-of-March reservoir level – 1206.0 feet
    • Notes: The Gavins Point release will be increased around March 15 to begin providing minimum service navigation flow support on the lower Missouri River.
       
  • Fort Randall Dam
    • Average releases past month – 7,100 cfs
    • End-of-February reservoir level – 1352.1
    • Forecast end-of-March reservoir level – 1354.8 feet
    • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point and to back up the Gavins Point release increases.  The reservoir will refill to near elevation 1355 by the end of March.
       
  • Big Bend Dam
    • Average releases past month – 12,400 cfs
    • Forecast average release rate – 20,600 cfs
    • Forecast reservoir level – 1421.0 feet
       
  • Oahe Dam
    • Average releases past month – 10,800 cfs
    • Forecast average release rate – 21,100 cfs
    • End-of-February reservoir level – 1603.6 feet
    • Forecast end-of-March reservoir level – 1603.3 feet
       
  • Garrison Dam
    • Average releases past month – 24,900 cfs
    • Current release rate – 16,000 cfs
    • Forecast average release rate – 16,000 cfs
    • End-of-February reservoir level – 1835.1 feet
    • Forecast end-of-March reservoir level – 1834.6 feet
    • Notes – Releases were gradually reduced from 25,000 cfs to 16,000 cfs near the beginning of March.
       
  • Fort Peck Dam
    • Average releases past month – 5,400 cfs
    • Current release rate – 5,000 cfs
    • Forecast average release rate – 5,000 cfs
    • End-of-February reservoir level – 2230.4 feet
    • Forecast end-of-March reservoir level – 2230.9 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.

Hydropower:

The six mainstem power plants generated 467 million kWh of electricity in February. Typical energy generation for February is 618 million kWh. Forecast generation for 2024 is 8.3 billion kWh 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://go.usa.gov/xVgWr.

MISSOURI RIVER MAINSTEM RESERVOIR DATA

 

Pool Elevation
(feet above mean sea level)

Water in Storage
(1,000 acre-feet)

 

On February 29

Change in February

On February 29

% of 1967-2023 Average

Change in February

Fort Peck

2230.4

+1.0

14,035

97

+203

Garrison

1835.1

-1.8

17,030

96

-538

Oahe

1603.6

+3.6

17,486

99

+1,032

Big Bend

1420.6

-0.2

1,666

98

-9

Fort Randall

1352.1

+6.8

3,164

95

+506

Gavins Point

1206.6

-0.8

340

87

-20

 

 

Total

53,721

97

+1,174

 

WATER RELEASES AND ENERGY GENERATION FOR FEBRUARY

 

Average Release in 1,000 cfs

Releases in 1,000 acre-feet

Generation in Million kWh

Fort Peck

5.4

308

43

Garrison

24.9

1,430

214

Oahe

10.8

621

90

Big Bend

12.4

712

40

Fort Randall

7.1

407

43

Gavins Point

13.0

748

35

 

 

Total

465


Contact
Eileen Williamson
40-996-3802
eileen.l.williamson@usace.army.mil

Release no. 24-006