US Army Corps 1616 Capitol Avenue
of Engineers Omaha, Nebraska 68102
Public Affairs Office
Release No.09-002 Date: February 9, 2009
Water Management Monthly News Release
OMAHA – The normal mountain snowpack is providing Missouri River water users a glimmer of hope for continued recovery of water storage in the six big reservoirs.
Given that the mountain snowpack is near normal for this time of the year, but the plains snowpack is below normal, the current forecast for runoff in 2009 is 22.3 MAF, 90 percent of average. If the forecast verifies, the level of Oahe is forecasted to peak near 1596 feet this summer. Garrison is forecast to peak near 1829 feet and Fort Peck near 2217 feet.
“The snowpack is a good sign, but it’s too early to be very optimistic about significant recovery,” said Larry Cieslik, Chief of the Water Management office here. “2008 was the first year since 1999 with runoff above the normal 24.8 MAF. The higher inflows helped, but another major contributor to the higher reservoir levels was the weeks of low releases due to good downstream tributary inflow. It remains to be seen if downstream inflow will be good again this year.”
The 2009 Annual Operating Plan was published in late December. It contains a detailed description of continued drought conservation measures because reservoir levels are still below normal. There will be reduced navigation support, reduced hydropower generation, and lower than desired reservoir levels.
There will be two “spring pulses” released from Gavins Point Dam this year, one in March and one in May. The pulses are required to comply with the 2003 Amended Biological Opinion of the U.S. Fish and Wildlife Service. The opinion identified pulses in the spring from Gavins Point as part of the Reasonable and Prudent Alternative to avoid jeopardizing the continued existence of the endangered pallid sturgeon as required by the Endangered Species Act.
The plan includes “flood control constraints” as described in the Master Water Control Manual. These are the river levels that act as triggers for reducing releases from Gavins Point during high downstream flows. Both pulses may be reduced or eliminated due to these limits. An additional safeguard is the use of observed and anticipated rainfall into the daily river forecast to provide greater assurance that flows will remain below the limits.
Timing of the March pulse will correspond with the annual increases in releases to meet navigation targets at Sioux City, Omaha, Nebraska City and Kansas City. The water needed for both pulses will be gradually staged in Fort Randall reservoir prior to their implementation, further reducing negative impacts to storage in the three large upper reservoirs of Oahe, Garrison and Fort Peck.
The plan anticipates that there will be minimum flows at the start of the navigation season which could be shortened by 0 to 22 days, depending on runoff this winter and spring. A final determination on season length will be made on July 1, 2009.
Steady to rising reservoir levels during the spring fish spawn at the three large upper reservoirs are likely if there is normal or above normal runoff. However, continued drought conditions may not make that possible at all three. If that is the case, the Corps will set releases at Garrison Dam to result in a steady to rising pool during April and May, to the extent reasonably possible. The ability to provide such conditions depends on the volume, timing and distribution of the runoff from melting snow on the plains and in the mountains of Montana and Wyoming.
Gavins Point releases averaged 12,900 cfs in January. They were reduced to 10,000 cfs early this month with the arrival of moderate temperatures. They will be adjusted as necessary during periods of cold weather to allow downstream intakes to remain operational. The average release for February is 17,400 cfs.
Fort Randall releases averaged 10,900 cfs in January. They will be adjusted this month as necessary to maintain Gavins Point reservoir near its desired elevation. Fort Randall reservoir rose almost 6 feet during January due to hydropower production releases from Oahe Dam.
Big Bend reservoir will remain in its normal range of 1420 to 1421 feet. Releases will be adjusted to meet hydropower needs.
Oahe reservoir remained essentially level in January, ending at elevation 1593 feet msl. Releases averaged 14,800 cfs during the month and will average 12,800 cfs in February to meet power generation needs. The reservoir will rise a foot, ending near elevation 1594 feet msl, 6.1 feet below its normal elevation. The reservoir is currently 10.7 feet higher than it was last year at this time.
Garrison reservoir fell 0.7 feet in January, ending at elevation 1824 feet. Releases averaged 15,700 cfs during the month, compared to the long-term average of 22,800 cfs. The reservoir is expected to fall half a foot in February, ending at 1823.4 feet, 7.2 feet below normal. It is currently 14.9 feet higher than last year at this time.
Fort Peck reservoir rose 0.2 foot in January, ending at elevation 2209.9 feet msl. Releases averaged 6,000 cfs, compared to the long-term average of 10,900 cfs. The reservoir will climb nearly a foot in February, ending at elevation 2210.7 feet, 16.2 feet below normal. It is currently 11 feet higher than last year at this time.
The six main stem power plants generated 471 million kilowatt hours (kWh) of electricity in January, only 65 percent of normal because of lower pool levels and reduced releases from the dams. Total energy production for 2009 is forecast to total 7.1 billion kWh, compared to the average of 10 billion kWh.
# # #
View daily and forecasted reservoir and river information on the Water Management section of the Northwestern Division homepage at www.nwd.usace.army.mil.
MISSOURI RIVER MAIN STEM RESERVOIR DATA
WATER RELEASES AND ENERGY GENERATION FOR JANUARY
|© 2011 WaterWebster.org All rights reserved. Acceptable Use Policy | Privacy Statement Policy|