Drought Conditions Driving Lowered Missouri River Runoff Forecast


Very dry conditions in April resulted in low runoff in the upper Missouri River Basin. Runoff was 44 percent of average, the 9th driest April in 123 years of record. The updated 2021 upper Basin runoff forecast is 17.8 million acre-feet, 69 percent of average, the 22nd lowest calendar year runoff volume.

John Remus of the Army Corps of Engineers says, “The extremely dry April, current drought conditions, and below-normal mountain snowpack has led our office to significantly lower the 2021 calendar year runoff forecast.” Mountain snowpack in the upper Basin has peaked and melting is underway. The mountain snowpack peaked above Fort Peck in late March at 86 percent of normal, and the Fort Peck to Garrison reach peaked in late April at 96 percent of average. Gavins Point Dam releases will provide full-service navigation flow support through July 1. That, in combination with the Bank Stabilization and Navigation Project, is generally sufficient to provide an adequate channel.