Rainfall in the Missouri River Basin above Sioux City, Iowa, was above normal during August, resulting in above-average runoff. However, because of drier-than-normal conditions in previous years, total storage in the Missouri River reservoir system remains lower than normal. Based on September 1 system storage, releases from the Gavins Point Dam will be 13,000 cubic feet per second, slightly above the minimum rate.
“August rainfall provided some inflow into the Upper Missouri River Basin Reservoir System,” says John Remus, chief of the Army Corps’ Missouri River Basin Water Management System. “Some areas received up to 400 percent of normal rainfall.”
August runoff was 1.7 million acre-feet, 121 percent above average in Sioux City. The updated 2023 forecast for the upper basin is 29.1-million-acre feet, 113 percent of average. The annual average runoff for the upper basin is 25.7-million-acre fee. The total volume in the System was 55.5 MAF on September 1.
