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For Immediate Release: April 6, 2012
Corps begins April with full capacity of flood control storage, continues monitoring weather conditions
Omaha, Neb. — Unusually warm and dry conditions in the Missouri River basin during the month of March resulted in below normal runoff into the mainstem reservoir system for the first time since November 2010.
As a result, the total volume of water stored in the reservoir system on April 1 was 56.9 million acre-feet, leaving 16.2 of the 16.3 MAF of flood control storage available.
Runoff above Sioux City, Iowa was 78 percent of normal bringing in 2.2 MAF of water. Though March was dry in comparison to recent years, it was the 40th driest March in the last 114 years of detailed record-keeping by the Corps.
"The lack of plains snowpack and lower than normal mountain snowpack indicates that we are likely to see below normal runoff during the months of May, June and July," said Jody Farhat, Chief of the Missouri River Basin Water Management Division. "But it’s still early. As we learned last year, conditions on the ground can change very quickly so we will continue to monitor conditions in the basin and make any necessary release adjustments as the spring unfolds."
The current forecast for the 2012 calendar year calls for 23.4 MAF of runoff above Sioux City, Iowa, 94 percent of normal. A normal runoff year typically brings in 24.8 MAF of water. Runoff for the 2011 calendar year totaled 61 MAF, 246 percent of normal and the highest in 114 years.
On April 1, system storage was 56.9 million acre feet, just 0.1 MAF above the base of the annual flood control pool. The annual flood control pool is the desired operating zone for the reservoir system because it allows the Corps to serve all eight congressionally authorized purposes: flood control, navigation, water supply, irrigation, hydropower, recreation, water quality control and fish and wildlife.
In mid-March the Corps began incrementally increasing releases out of Gavins Point Dam from 22,000 cubic feet per second to 28,500 cfs in support of the 2012 navigation season which began April 1 near St. Louis. "We expect to provide full-service flow support for navigation this year based on the current forecast," said Farhat. "However, the actual flow support for the second half of the navigation season and the season length will be based on the July 1 system storage check."
Because reservoir system storage is near normal levels, the Corps will provide what is referred to in the Mast er Manual as "full-service navigation." In other words, the Corps will release enough water from Gavins Point Dam to meet flow targets along the river designed to provide a 735-mile navigation channel, 9 feet deep by 300 feet wide from Sioux City, Iowa to St. Louis, Mo. If drought conditions develop in the basin, flow support may be reduced to conserve water in the reservoirs.
As of April 1, mountain snowpack was 97 percent of normal above Fort Peck and 86 percent of normal from Fort Peck to Garrison. Normally, 96 percent of the peak accumulation occurs by April 1. Mountain snowpack normally peaks April 15. According to Natural Resource Service Conservation reports, mountain snowpack in southern Montana and northern Wyoming has started melting with significant amounts of snowmelt at lower elevations. In northern Montana, some accumulation is still occurring.
At this time last year, mountain snowpack was 116 percent of normal above Fort Peck and 112 percent of normal from Fort Peck to Garrison and was still accumulating.
View mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdfView plains snowpack graphic/comparison to last year here: http://www.nwo.usace.army.mil/pdfs/SnowpackComparison2012v2011.pdf
Following last year’s record breaking runoff season, Beth Freeman, regional administrator for FEMA Region VII, reminds citizens within the basin to consider purchasing flood insurance. Localized flooding can occur anytime as a result of heavy rains, so citizens should not become complacent with regard to buying insurance just because recent conditions have been drier than normal.
"Regardless of whether you live in or out of a designated floodplain, flood insurance can mean the difference between a quick recovery with new possibilities, or the uncertainty that accompanies disaster recovery without it," Freeman said. For more information on flood insurance, visit: http://www.floodsmart.gov
Spring Public MeetingsThe Corps will hold a series of public meetings in seven cities throughout the basin beginning April 16 to provide an update on current hydrologic conditions in the Missouri River basin and planned regulation of the mainstem reservoirs during the coming months.
The schedule for the Bismarck spring meeting is as follows:
April 16Bismarck, N.D.Open House – 6 p.m.Public Meeting – 7 p.m.Bismarck Civic CenterExhibit Hall315 South 5th Street
Reservoir Forecasts Gavins Point releases averaged 23,900 cubic feet per second in March. Releases are currently 28,500 and are expected to reach 29,000 by the end of April. The reservoir’s elevation is currently 1205.9 feet mean sea level, which is normal for this time of year. It is expected to remain near 1206 throughout the month.
Fort Randall releases averaged 21,100 during March. Releases in April are expected to average 26,300 cfs. The reservoir ended the month near elevation 1353. It is expected to increase by 2.2 feet to 1355.2 by the end of the month.Big Bend releases averaged 21,100 in March. They are expected to average 27,400 cfs during the month of April. The reservoir will remain near its normal elevation of 1420 feet during the month.
Oahe releases averaged 22,300 during the month of March. The reservoir ended the m onth at elevation 1605.8 feet, up 0.2 feet from the previous month. It is expected to end April 0.5 feet higher than last month near elevation 1606.3 feet.
Garrison releases averaged 20,500 in March. Releases are expected to average 26,000 cfs in April. The reservoir ended March at elevation 1838 feet, level to where it was at the end of March. It is forecast to end April at elevation 1837.8.
Fort Peck releases averaged 6,800 cfs during March. Releases are expected to average 8,500 during the month of April. The reservoir ended the month at elevation 2234.9 feet, down 0.7 feet from the previous month. It is expected to end April at 2235.1 feet.
The reservoir releases and elevations discussed above should not be assumed to be definitive. Additional heavy precipitation in the basin could cause adjustments to the reservoir release rates.
The six mainstem power plants generated 738 million kilowatt hours (kWh) of elec tricity in March. Typical power generation for the month of March is 554 million kilowatt hours. The power plants are projected to generate 10 billion kilowatt hours during calendar year 2012, which equates to the long-term average.
To view the detailed three-week release forecast for the mainstem dams, go to: http://www.nwd-mr.usace.army.mil/rcc/reports/twout.html.