OMAHA, NE — The U.S. Army Corps of Engineers (Corps) Missouri River Basin Water Management Division reports runoff in the Missouri River Basin above Sioux City, Iowa, for the month of July was 2.7 million acre feet (MAF), 81 percent of normal. The 2015 runoff forecast is 25.0 MAF, 99 percent of normal. Average annual runoff is 25.2 MAF.

The total volume of water stored in the Mainstem Reservoir System is currently 61.3 MAF, occupying 5.2 MAF of the 16.3 MAF combined flood control storage zones. “System storage peaked on July 9 at 61.9 MAF and is gradually declining. The water currently stored in the annual flood control zone will be released during the remainder of the year to serve navigation, water supply and other downstream purposes and will be completely evacuated prior to the start of next year’s runoff season,” said Farhat.

As previously announced, the Corps will be providing flows to support full service navigation as well as a full eight-month navigation season. Full service flow support is generally sufficient to provide a navigation channel that is 9 feet deep and 300 feet wide. “Gavins Point releases will be adjusted as necessary to meet full service navigation targets in reaches with commercial navigation,” added Farhat.

The August reservoir regulation  studies also indicate that Gavins Point winter releases will likely range from 17,000 to 20,000 cfs, which is slightly higher than the normal range of 12,000 to 17,000 cfs. Winter releases at this level provide good service to municipal and industrial water intakes along the lower Missouri River during periods of ice formation, which can reduce river stages and impact the facilities.

The Corps will continue to monitor basin conditions and fine tune the regulation of the reservoir system based on the most up-to-date information.

Reservoir Forecasts

Gavins Point Dam releases averaged 27,000 cfs in July. Releases are currently 27,000 cfs and will be adjusted to meet downstream targets. The reservoir behind Gavins Point Dam ended July at elevation 1206.4 feet. The reservoir elevation will remain near that level during August.

Fort Randall Dam releases averaged 25,300 cfs in July. Fort Randall releases will be adjusted as necessary to maintain the desired elevation at Gavins Point. The reservoir ended July at elevation 1358.4 feet, down 1.8 feet during the month. The reservoir is forecast to drop about 2 feet during August.

Big Bend Dam releases averaged 19,600 cfs during the month of July. Releases will average near 23,000 cfs in August. The reservoir will remain near its normal elevation of 1420 feet.

Oahe Dam releases averaged 20,800 cfs during the month of July. Releases will average near 23,000 cfs in August. The reservoir ended July at elevation 1613.3 feet, up 0.5 feet during the month. The reservoir is expected to fall approximately 1 foot during August.

Garrison Dam releases averaged 20,800 cfs in July. Releases will be reduced from 21,000 cfs to 20,000 cfs on August 6. Garrison ended the month at elevation 1844.3 feet, down 0.2 feet from June 30. It is expected to fall one to two feet during August.

Fort Peck Dam releases averaged 8,100 cfs in July. Releases will remain near that rate during August. The reservoir ended July at elevation 2236.2 feet, down 0.7 feet. The reservoir is forecasted to fall less than 2 feet by the end of August.

The forecasted 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.

The six mainstem power plants generated 799 million kilowatt hours (kWh) of electricity in July. Typical energy generation for the month of July is 946 million kWh. The power plants are projected to generate 8.8 billion kWh of electricity this year, compared to the normal of 10 billion kWh.

To view the detailed three-week release forecast for the mainstem dams, go to: http://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf.

MISSOURI RIVER MAINSTEM RESERVOIR DATA

WATER RELEASES AND ENERGY GENERATION FOR JULY

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