OMAHA, Nebraska (USACE)   – Widespread and heavy rainfall in the Missouri River basin above Sioux City, IA (upper basin) resulted in another month of much above average runoff. Precipitation during September was more than 200 percent of normal in eastern Montana, much of North Dakota, portions of South Dakota and northern Nebraska. As a result, September runoff into the upper basin above Sioux City, was nearly twice the record runoff, which was recorded in 1986.

 

Runoff in the Gavins Point to Sioux City reach was more than 16 times the long-term average and more than twice the previous record. Runoff in the Fort Randall to Gavins Point reach was over 4 times average and almost twice the previous record. Runoff between Oahe and Fort Randall was over 12 times average and set a new record. Runoff between Garrison and Oahe was over 4 times average. Finally, runoff between Fort Peck and Garrison was over 2 times average and is the second highest runoff of record, and Fort Peck was 1.5 times average.

 

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