Although the overall runoff in September was above average in the upper Missouri River Basin, the runoff at the Fort Peck and Garrison reaches continues to be well below average.
“Beneficial rainfall occurred over central South Dakota and North Dakota in September, resulting in well-above average runoff into Oahe, Big Bend, Fort Randall, and Gavin’s Point,” said John Remus, Chief of the U.S. Army Corps of Engineers Water Management Division. “The above-average runoff combined with the lower releases from Gavin’s Point slightly improves the System storage outlook for the beginning of the 2026 runoff season.”
September runoff was 1.3 million acre-feet, 109 percent of the average above Sioux City, Iowa. As of October 1, the total volume of water stored in the system was 50.4-million-acre feet, which is 5.7 million below the base of the system’s flood control zone. System storage will continue to decline through the fall.
