Dakota Country Magazine October 2016 Edition - Page 20

MISSOURI RIVER UPDATE Below average runoff continues Summer inflows well below normal, adjustments being made OMAHA, Neb. -August runoff in the Missouri River Basin above Sioux City, Iowa, was 1.0 million acre feet (MAF), 76 percent of average, according to the U.S. Army Corps of Engineers. This marks the third consecutive month with below average runoff in the upper basin. The 2016 calendar year runoff forecast is 22.4 MAF, which is 89 percent of the historic average. The total volume of water stored in the Mainstem Reservoir System on September 1 was 58.1 MAF, occupying 2.0 MAF of the 16.3 MAF combined flood control storage zones. “Water captured in the reservoirs during spring and summer is being released during the drier months to serve navigation, irrigation and other authorized purposes,” said Jody Farhat, chief of the Corps’ Missouri River Basin Water Management Division. System storage peaked on June 22 at 60.1 MAF, occupying 25 percent of the available flood storage. The Corps is providing a full 8-month navigation season with full service flow support based on the July 1 storage check. Full service flow support at the mouth of the Missouri River will end December 1. Based on the September 1 system storage, Gavins Point Dam winter release will be at least 17,000 cfs. This release rate is generally sufficient to meet the needs of downstream water intakes during the winter, but may be increased slightly during periods of ice formation on the lower river. Winter releases are normally near 17,000 cfs. “Full service naviga- tion support and normal winter releases should be sufficient to evacuate all water stored in the flood zones of the reservoirs prior to the start of next year’s runoff season,” said Farhat. ”However, releases will be adjusted as needed in response to changing basin conditions throughout the fall and winter.” Reservoir Forecasts Gavins Point releases averaged 25,000 cubic feet per second (cfs) during August, reduced to 23,000 cfs in early A storm approaches the dam at Lake Oahe north of Pierre. Page 20, Dakota Country, October 2016 www.dakotacountrymagazine.com