Lower Than Normal Runoff Expected For Missouri River Basin
January runoff in the Missouri River Basin above Sioux City, Iowa, was 1.0 million acre-feet, which is 132 percent of average. Runoff was above average for all of the reaches in the upper Missouri River Basin, even though most of the upper Basin had below-normal precipitation. This was due to above average temperatures causing early snowmelt.
The updated 2026 calendar year runoff forecast for the Missouri River Basin above Sioux City continues to be below average.
“Runoff into the reservoir system was above average for the month of January despite the dry conditions across the basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “With the below-average plains and mountain snowpack, we are forecasting a below-average runoff year for the Basin, resulting in reduced flows from the reservoirs, particularly in the upper basin.”
The 2026 calendar year mnoff forecast above Sioux City is 23.4 MAF, 91 percent of average.
At the start of the 2026 runoff season, which typically begins around March 1, the total volume of water stored in the Missouri River Mainstem Reservoir System is expected to be 48.9 MAF, 7.2 MAF below the top of the carryover multiple use zone.
“While the target winter release from Gavins Point Dam is 12,000 cfs, releases were increased to 14,000 cfs in mid-January to mitigate some of the effects of the much colder temperatures across the lower basin,” said Remus. “Releases will be held steady until ice effects stabilize downstream of Gavins, at which time releases will be reduced to the winter release of 12,000 cfs. Flows will continue to be adjusted to the extent practical based on cold weather conditions,” 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-todate information.
Navigation flow support for the Missouri River is forecast to be at 5,500 cfs below full-service for the first half of the 2026 season, which begins April 1 at the mouth of the river near St. Louis, Mo. 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 snowpack in the upper Missouri River Basin is accumulating at below average rates. The Feb. 3 mountain snowpack in the Fort Peck reach was 81 percent of average, while the mountain snowpack in the Fort Peck to Garrison reach was 90 percent of average. By Feb. 1, about 60 percent of the total mountain snowfall has typically accumulated. Mountain snow normally peaks near April 17. The mountain snowpack graphics can be viewed at: https://go.mil/mrmtn-
https://go.mil/mr-
snowpack. Additionally, the plains snowpack is below normal in the upper Missouri River Basin.
Fort Peck Dam
Average releases past month - 5,000 cfs Current release rate - 5,000 cfs Forecast average release rate - 5,000 cfs F.nd of January reservoir level - 2221.7 feet Forecast end-of-February reservoir level - 2221.9 feet Notes: Releases will remain at 5,000 cfs in February.
