June runoff in the Missouri River Basin above Sioux City, Iowa, was 3.3 million acre-feet, 60 percent of the average. The updated 2025 calendar year runoff forecast for the Missouri River Basin above Sioux City is below average. Mountain snowpack melted more rapidly than normal, and all reaches except the Sioux City reach experienced below normal precipitation during June,” said John Remus of the Army Corps of Engineers. “The June runoff was less than forecast, and dry conditions will continue in July.”
The June 2025 runoff forecast above Sioux City is 19.1 million acre-feet, 74 percent of the average and slightly lower than last month’s forecast. System storage on July 1 was 52.1 million acre-feet, four million below the top of the carryover multiple-use zone. The monthly study indicates that the winter release from Gavins Point will likely be at the minimum rate of 12,000 cubic feet per second.
-NAFB