April Showers Brought Some Relief In Missouri Basin

Spring precipitation brought much-needed moisture to the Missouri River Basin, boosting the Corps of Engineers’ forecast for total 2024 runoff.

“While the calendar year forecast remains below average, the runoff forecast continues to improve thanks to higher-than-expected rainfall in April,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “We hope to see the precipitation trend continue to provide the much-needed moisture for the region.”

Forecast Increased

The Corps’ annual runoff forecast for the upper Missouri River Basin above Sioux City, Iowa, is 19.2 million acre feet (maf.), a full 1.7 maf. higher than last month’s forecast.

Soil moisture is above normal in South Dakota, below normal in eastern Montana and western North Dakota and near normal for the rest of the upper basin, the Corps said. Drought or abnormally dry conditions are currently present in 52 percent of the basin. Drought conditions in most of the upper basin are likely to persist during May, the Corps said.

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“Despite the additional moisture, much of the upper basin remains in drought and is expected to remain in drought through the month of May,” Remus said. “However, drought conditions in the lower basin are expected to improve or be removed during May. The system is still recovering from drought as we continue to serve all congressionally authorized purposes.”

Mountain snowpack was below normal all season long and peaked approximately one week earlier than normal.

Total system storage is currently 49.9 maf., 6.2 maf. below the top of the carryover multiple use zone.

Navigation Support

Gavins Point Dam releases will continue to provide navigation flow support at 500 cfs. below full service for the first half of the navigation season. The flow support season 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, which was 54.1 maf., 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.