Corps Forecasts Drier-Than-Normal Year In Missouri River Basin

In the upper Missouri River basin, the year 2024 is starting off much as last year ended: with lower-than-normal water levels. The Corps of Engineers’ forecast for this year continues to call for below-average runoff in the basin.

January runoff in the Missouri River basin above Sioux City, Iowa, was 0.4 million acre-feet (maf.), 56 percent of average. Runoff was well below average due to much-below-normal temperatures over the whole Missouri River basin and below-normal precipitation over most of the upper basin.

“The runoff into the reservoir system was well below average for the month of January,” said John Remus, chief of the Corps of Engineers’ Missouri River Basin Water Management Division. “This fact, in conjunction with the below-average plains and mountain snowpack, indicates a below-normal runoff year for the basin.”

The 2024 calendar year runoff forecast above Sioux City is 18.8 maf., 73 percent of average. The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack and long-term precipitation and temperature outlooks.

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At the start of the 2024 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 52.7 maf., 3.4 maf. below the top of the carryover multiple use zone.

Gavins Point Releases

To conserve water in the system, releases from Gavins Point Dam—the lowest dam on the system—are scheduled to be 13,000 cubic feet per second (cfs.) this winter while still serving the needs of the municipal, industrial and powerplant water intakes along the lower river.

“While the target winter release from Gavins Point Dam is 13,000 cfs., releases were increased to 15,000 cfs. in mid-January to mitigate some of the effects of the much colder temperatures across the lower basin,” Remus said. Releases were reduced to 13,000 cfs. at the end of the month and will be held at that rate through February.

“With weather conditions and river stages forecast to be more seasonal over the next few weeks, system releases are returning to the target winter rates,” Remus said.

Navigation flow support for the Missouri River is forecast to be at 1,500 cfs. below full service for the first half of the 2024 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.