Missouri River Runoff Continues Below Average Forecast
The updated 2025 calendar year runoff forecast for the Missouri River Basin above Sioux City, Iowa, continues to be below average. March runoff in the Missouri River Basin above Sioux City was 2.3 million acre-feet, 76 percent of average.
“Runoff into the reservoir system was below average for the month of March and conditions across most of the basin remain dry,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “Mountain snowpack has improved over the last few weeks but is still below average. We are forecasting a below-average runoff year for the basin,” Remus stated.
The 2025 calendar year runoff forecast above Sioux City is 21.9 MAF, 85 percent of average. The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack and long-term precipitation and temperature outlooks.
The volume of water stored in the Missouri River Mainstem Reservoir System is currently 50.8 MAF, 5.3 MAF below the top of the carryover multiple use zone.
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-todate information.
Navigation Beginning in mid-March, releases from Gavins Point Dam were adjusted to provide flow support for Missouri River navigation. Navigation flow support for the Missouri River is at 4,000 cubic feet per second below full-service for the first half of the 2025 season, which began April 1 at the mouth of the river near St. Louis, Mo. The service level was 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.
Spring Public Meetings
The Missouri River Basin Water Management Division held two virtual public meetings the week of April 7. The meetings provided a status update of basin conditions, mountain snowpack, runoff, and planned operations for the year to meet the authorized purposes for the reservoir system.
The recording of the meeting and supporting slides are available at https://www. nwd.usace.army.mil/mrwm/ public-meetings/.
Reservoir Forecasts Garrison Dam Average releases past month – 17,600 cfs Current release rate – 18,000 cfs Forecast average release rate – 18,000 cfs End-of-March reservoir level – 1831.4 feet Forecast end-of-April reservoir level – 1831.2 feet Fort Peck Dam
Average releases past month – 5,600 cfs Current release rate – 7,000 cfs Forecast average release rate – 7,000 cfs End-of-March reservoir level – 2227.6 feet Forecast end-of-April reservoir level – 2227.5 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 610 million kWh of electricity in March. Typical energy generation in March is 636 million kWh. Forecast generation for 2025 is 8.9 billion kWh compared to the long-term average of 9.4 billion kWh.
