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 June was 6.8 million acre feet (MAF), 125 percent of normal.  The 2015 runoff forecast is 26.6 MAF, 105 percent of normal.  Average annual runoff is 25.2 MAF. 

June precipitation was above normal across much of the Missouri River Basin, most notably in the western Dakotas, eastern Montana and eastern Wyoming.  Heavy rain also fell in eastern Nebraska, northeastern Kansas and much of Missouri.  “In response to repeated rains in the lower basin, releases from Gavins Point Dam were reduced to 22,000 cubic feet per second (cfs) to reduce flood risk along the Missouri River,” said Jody Farhat, chief of the Missouri River Basin Water Management Division.  “Following the flood crest, Gavins Point releases were gradually increased to meet the navigation flow targets.”

The total volume of water stored in the Mainstem Reservoir System is currently 61.9 MAF, occupying 5.8 MAF of the 16.3 MAF combined flood control storage zones.  “The reservoirs are currently utilizing 35 percent of the available flood control storage and remain well positioned to capture additional runoff should further reductions in releases become necessary,” stated Farhat.

Based on the July 1 system storage check, the navigation service level will remain at full service and there will be a full 8-month season.  Full service flows are generally sufficient to provide a navigation channel 9-feet deep by 300-feet wide.   Navigation flow support typically ends on December 1 at the mouth of the Missouri River near St. Louis, however a 10-day extension to the navigation season length may be provided this year if needed to evacuate water stored in the flood control zones of the mainstem reservoirs.

The melting of the mountain snowpack is complete.  This year’s below normal mountain snowpack peaked at 72 percent of normal in the reach above Fort Peck Dam and 78 percent of normal in the reach from Fort Peck to Garrison dams.  View mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf.

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 24,600 cfs in June, ranging from 22,000 to 28,000 cfs.  Releases will remain near the current rate of 27,000 cfs in early July, and will be adjusted as necessary to meet downstream flow targets as tributaries flows decrease.  The reservoir behind Gavins Point Dam ended June at elevation 1206.3 feet.  The reservoir will remain near elevation 1206 feet during July.

Fort Randall Dam releases averaged 21,800 cfs during June.  Fort Randall releases are currently at 24,000 cfs and will be adjusted during July, as necessary, to maintain the desired elevation at Gavins Point. The reservoir ended June at elevation 1360.2 feet, up 4.1 feet during the month.  The reservoir is expected to fall approximately 2 feet during July. 

Big Bend Dam releases averaged 21,500 cfs during the month of June.  They are expected to average near 20,000 cfs this month. The reservoir will remain near its normal elevation of 1420 feet during July.   

Oahe Dam releases averaged 20,700 cfs during the month of June.  Releases are expected to average near 20,000 cfs this month. The reservoir ended June at elevation 1612.8 feet, up 2.8 feet during the month. The reservoir is expected to rise 1 foot during the month of July.

Garrison Dam releases averaged 21,000 cfs in June.  Releases will be held at 21,000 cfs in July.  Garrison ended June at elevation 1844.4 feet, up 5.9 feet.  It is expected to rise less than 1 foot during July.

Fort Peck Dam releases averaged 8,800 cfs in June.  Releases were reduced from 9,000 to 8,000 cfs on July 6.  Releases will likely remain near 8,000 cfs in July, but may be adjusted to provide adequate irrigation support below Fort Peck.  The reservoir ended June at elevation 2236.9 feet, up 0.9 feet.  The reservoir is forecasted to fall less than 1 foot during July.

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 756 million kilowatt hours (kWh) of electricity in June.  Typical energy generation for the month of June is 836 million kWh. The power plants are projected to generate 9.3 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

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WATER RELEASES AND ENERGY GENERATION FOR JUNE

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