Corps expects to reach intended storage level by start of runoff season

The Corps� Missouri River Basin Water Management Division, which operates the Missouri River main stem reservoir system, announced Friday that it has evacuated all but approximately 200,000 acre feet of floodwater from the system.

�Our current forecast shows system storage reaching the desired level of 56.8 million acre feet by March 1 in accordance with the Master Manual.  We are going to start the season a bit above the base of the annual flood control pool at both Fort Peck and Garrison reservoirs, but Oahe will be slightly below its annual flood control pool,� said Jody Farhat said, Chief of the Water Management Division here. �The reservoir system is in position to provide good levels of service to each of the congressionally authorized purposes, as well as to be prepared in the event that we experience a higher than normal runoff season.�

Both Fort Peck and Garrison Reservoirs are expected to begin the runoff season less than one foot above their annual flood control pool levels. Due to the need to make adjustments to releases at the reservoirs in December to avoid ice jams, the Corps did not evacuate as much water as was initially anticipated from the two reservoirs during the month of December.

The final 2010-2011 Annual Operating Plan was published in late December.  It is available in the Reports and Publications section of the Water Management website:

Runoff in 2010 totaled 38.8 MAF, the third highest in 113 years of record.  Storage peaked in the Missouri River main stem system of reservoirs at 65.9 MAF on July 23, 2010; it currently sits at 57 MAF. The current forecast for the 2011 runoff year is 27.8 million acre feet, 112 percent of normal.

The mountain snowpack is 116 percent of normal for this time of year.  Traditionally, about 42 percent of the peak accumulation occurs by January 1.  The plains snowpack is above normal over most of the upper Missouri River basin.

Gavins Point releases averaged 25,200 cfs in December compared to the long-term December average of 19,200 cfs.  Releases from Gavins Point will be increased from 17,000 cfs to 19,000 cfs in early January.  Releases are forecasted to average 18,500 cfs during the month of January, and 20,000 cfs for February. The reservoir level is expected to remain essentially level throughout the month of January, ending the month at an elevation of 1207.5 feet msl.

Fort Randall releases averaged 22,800 cfs in December. The reservoir climbed 2.2 feet in December, ending near elevation 1340.5 feet.  Its elevation is projected to increase more than 4 feet in January as it receives winter hydropower releases from Oahe and Big Bend.  Releases are expected to average 16,400 cfs in January. The long term average for this time of year is 15,100 cfs.

Big Bend reservoir will remain within its normal range between 1420 and 1421 feet. Releases will be adjusted to meet hydropower needs.

Oahe releases in December averaged 24,800 cfs and will average 20,500 cfs in January.  The reservoir ended December at elevation 1605, down 1.5 feet during the month.  The reservoir is currently 2.4 feet lower than it was last year at this time.

Garrison reservoir ended December at elevation 1841.6 feet, down 0.7 feet from November.  Releases were reduced as low as 16,000 cfs in early December prior to the river freeze-in.  After an ice cover was established releases were gradually increased to 22,000 cfs in early January.  River conditions will continue to be monitored and releases will be slowly increased to 25,000 cfs if conditions permit.  Releases averaged 17,800 cfs in December, and will average 24,000 cfs in January.  The reservoir is currently 4.1 feet into its annual flood control pool.

Fort Peck reservoir remained nearly level in December, ending at elevation 2235.3 feet msl. Releases averaged 7,800 cfs in December compared to the long-term average of 6,500 cfs.  The reservoir will drop slightly during the month, ending at elevation 2235 feet msl, nearly 7 feet above average.  It is currently more than 14 feet higher than last year at this time and was the last of the upper three large reservoirs to recover from the 2000 to 2007 drought.

The six main stem power plants generated 738 million kilowatt hours (kWh) of electricity in December, 106 percent of normal.  Total energy production for 2010 was 8.7 billion kWh compared to the long-term average of approximately 10 billion kWh.

View daily and forecasted reservoir and river information on the Water Management section of the Northwestern Division homepage at

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