Missouri River Flows Reduced To Winter Levels

The Corps of Engineers reduced releases from Gavins Point Dam to the winter release rate of 21,500 cubic feet per second (cfs.) on December 4, ending the navigation season on the Missouri River.

“Based on the September 1 system storage, Gavins Point Dam winter releases will be at least 17,000 cfs.,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “However, higher-than-normal runoff during the late summer and fall will allow us to provide a slightly higher release during the winter months. Higher winter releases will provide additional hydropower generation during the winter, which is one of the peak power demand periods. It will also benefit municipal and industrial water intakes below Gavins Point Dam, which can be impacted by low water levels during periods of ice formation.”

Gavins Point winter releases normally range between 12,000 and 17,000 cfs.

The total volume of water stored in the Missouri River mainstem reservoirs is currently 57.2 million acre-feet (maf.), occupying 1.1 maf. of the 16.3 maf. combined flood control storage zones, the Corps said.

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“System storage peaked on July 9 at 61.8 maf. and is declining, lowering 0.9 maf. in November,” Remus said. “During the winter, we will complete the evacuation of the system flood storage. At the beginning of next year’s runoff season, the full 16.3 maf. of flood control capacity will be available to capture runoff from rainfall and snowmelt.”

Runoff in the Missouri River Basin above Sioux City, Iowa, was 1.2 maf. during November, 110 percent of average. The 2017 calendar year runoff forecast is 29.4 maf., 116 percent of average. Average annual runoff is 25.3 maf.

The six mainstem power plants generated 703 million kwh. of electricity in November. Typical energy generation for November is 734 million kwh. The power plants are projected to generate 9.6 billion kwh. of electricity this year, compared to the long-term average of 9.3 billion kwh.

The Corps will continue to monitor basin conditions, including plains and mountain snow accumulation, and will adjust the regulation of the system based on the most up-to-date information.