Missouri River annual runoff forecast improves through April, still below average

OMAHA, Neb. (KCAU) — While April brought lots of rain to Siouxland and the Missouri River Basin, runoff was only 71% of average.

The U.S. Army Corps of Engineers gave their monthly report of conditions, reporting that there was 2.1 million acre-feet (MAF) of runoff for the basin above Sioux City, nearly 30% less than normal for the month.

The annual runoff forecast improved thanks to the April conditions, though, reaching 19.2 MAF, or 75% of average. That is 1.7 MAF higher than last month’s forecast.

“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 U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “We hope to see the precipitation trend continue to provide the much-needed moisture for the region.”

Soil moisture was also above normal in South Dakota but below normal in eastern Montana and western North Dakota. The rest of the upper basin was near normal. Even though most of northwest Iowa is no longer under any drought conditions , abnormally dry and drought conditions make up 52% of the Upper Missouri River Basin and are expected to continue through May.

“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 has been below normal all season long, peaking about a week earlier than normal, the release said.

The releases at Gavins Point Dam in Yankton, S.D. will be 500 cubic feet per second (cfs) below full service of navigational flow support for the first half of the season. The flow support season began April 1 at the mouth of the river near St. Louis, Missouri.

Releases at Gavins Point are currently 24,000 cfs with a forecast release of 31,000 cfs. It will be adjusted to provide minimum-service navigation flow support on the lower Missouri River.

The system storage is currently at 49.9 MAF, 6.2 MAF below the top of the carryover multiple use zone.

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