Drought conditions continue to impact the upper Missouri River Basin (above Sioux City, Iowa).
The US Army Corps of Engineers says July runoff in the upper Basin was 34% of average. July runoff above Fort Peck Dam was the lowest in 123 years of record-keeping.
Chief of the Corps’ Missouri River Basin Water Management Division John Remus says the updated 2021 upper Basin runoff forecast is 57% of average– or 14.6 million acre-feet. He says if realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on August 1 was 53.9 MAF, 2.2 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.
The US Drought Monitor shows approximately 75% of the Missouri River basin is currently experiencing some form of abnormally dry or drought conditions, an increase of 10% since the end of June. The seasonal drought outlook, which extends through the end of September, shows drought conditions will persist or expand across the upper basin.
Remus says per the July 1 system storage check, navigation support will be maintained at an intermediate service level, 1,500 cubic feet per second (cfs) below full-service levels, through the end of the normal 8-month navigation flow support season, which will end on Dec. 1.
Fall public meetings are currently scheduled to be held October 25-28 at several locations along the Missouri River. Locations and details will be forthcoming.
The forecast reservoir releases and elevations discussed above are not definitive. Additional precipitation, lack of precipitation or other circumstances could cause adjustments to the reservoir release rates.
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