OMAHA, Neb. — The Missouri River mainstem reservoir system enters the spring runoff season well prepared to capture spring runoff with slightly more than its full capacity of flood control storage available.
"It’s good news," said Jody Farhat, chief of the Water Management Division. "Our goal following the Flood of 2011 was to evacuate all of the flood waters and prepare the reservoir system for the 2012 runoff season. We’ve met that goal and have slightly more than the full capacity of the system available." During the fall and winter of each year, the corps completes the evacuation of stored flood water as part of its flood risk reduction efforts. The mild winter allowed the corps to make higher than normal releases throughout the winter. Gavins Point releases have been set on 22,000 cfs since mid-December. Normal winter release rates are near 17,000 cfs.
System storage fell as low as 56.1 million acre feet in late January, 0.7 MAF below the base of the annual flood control pool. However, higher than normal reservoir inflows during the month of February filled up some of the additional storage prior to March 1, the typical start of the runoff season. Runoff above Sioux City totaled 1.6 MAF in February, 153 percent of normal. This was due in part to a combination of high base flows from three consecutive years of above normal runoff and also warm temperatures which melted much of the river ice, freeing up water that usually flows into the reservoirs in March.
On March 1, system storage was 56.5 MAF, 300,000 acre feet below the base of the annual flood control zone. The annual flood control zone is the desired operating zone for the 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.
The forecast for runoff above Sioux City for calendar year 2012 is 26.1 MAF, slightly above the normal of 24.8 million acre feet. Mountain snow pack above Fort Peck is currently below normal at 93 percent of average. In the reach between Fort Peck and Garrison, mountain snow pack is tracking at 104 percent of average. This time last year, mountain snow pack was 110 and 107 percent of normal in the respective reaches. Traditionally, 79 percent of the peak mountain snow pack accumulation occurs by March 1.
View mountain snow pack graphic here: www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf
View plains snow pack graphic/comparison to last year here: www.nwo.usace.army.mil/pdfs/SnowpackComparison2012v2011.pdf
"Based on what we’re seeing today, runoff from the plains and mountain snow pack is expected to be near normal this year, however conditions can change dramatically as they did last spring" said Farhat. "The most important thing for people living along the river to be aware of is the potential for rainfall driven flood events." Historically, localiz ed rainfall driven flood events occur somewhere along the river almost every year, Farhat said.
Releases from Gavins Point dam will be increased incrementally beginning in mid-March for the 2012 navigation season, which will open on April 1 at the mouth of the river near St. Louis, Mo. Full-service flow support will be provided for navigation and other downstream uses during the first half of the navigation season. The level of flow support for the second half of the navigation season and the season length will be made following the system storage check on July 1. Full-service flows range from 31,000 cfs at Sioux City to 41,000 cfs at Kansas City and are designed to provide a 300 foot wide by 9 foot deep channel from Sioux City to the mouth. The navigation season opening dates at other locations are:
March 23 – Sioux City, Iowa
March 25 – Omaha, Nebraska
March 26 – Nebraska City, Nebraska
March 28 – Kansas City, Missouri
Steady to rising reservoir levels during the forage fish spawn at the three large upper reservoirs (Fort Peck, Garrison and Oahe) are likely if there is normal or above normal runoff. However, if runoff is below normal, the corps will set releases to result in steady to rising pools at Fort Peck and Oahe, to the extent possible. The forage fish spawn generally occurs from early April through mid-June.
The spring pulses from Gavins Point Dam in March and May for the benefit of the endangered pallid sturgeon are not planned this year due in part to last year’s extensive flooding. The pulses are part of the 2003 Amended Biological Opinion of the U.S. Fish and Wildlife Service. The opinion identified the pulses 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.
A series of seven public meetings will be conducted throughout the basin during the week of April 16 -20 to update stakeholders on current hydrologic conditions and the planned operation of the reservoir system through 2012. Detailed information, including times and locations, will be announced as soon as arrangements have been finalized.
Reservoir Forecasts
Gavins Point releases averaged 22,000 cfs in February. The reservoir’s elevation is currently 1206.5 feet mean sea level. It will be lowered to 1206 by the end of March.
Fort Randall releases averaged 18,700 during February. Releases in March are expected to range from 18,000 cfs to 22,000 cfs as necessary to maintain the level of Gavins Point reservoir. As part of its normal refill, the reservoir’s elevation is expected to increase from its current elevation of 1350.7 feet to near 1355, by the end of March.
Big Bend releases averaged 21,000 in February. They are expected to aver age 22,600 cfs during the month of March. The reservoir will remain near its normal elevation of 1420 feet during the month.
Oahe releases averaged 22,400 during the month of February. The reservoir ended the month at elevation 1605.6 feet, up 0.5 feet from the previous month. It is expected to end March near elevation 1607.
Garrison releases ranged from 22,000 cfs to 25,000 cfs in February. Releases will be gradually reduced from 22,000 cfs to 17,500 cfs during March. The reservoir ended February at elevation 1838 feet, down 0.2 foot during the month. The reservoir is forecast to end March at elevation 1838.7. The corps continues to monitor the Missouri River near Bismarck, N.D., closely for potential ice jam flooding and will adjust reservoir releases if necessary.
Fort Peck releases averaged 10,800 cfs during February. Releases were reduced from 12,000 cfs to 9,000 cfs during the month. Releases will be decreased to 6,500 in early March. The reservoir ended the month at elevation 2234.2 feet, down 1.4 feet from the previous month. It is expected to end March at 2235.6 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 637 million kilowatt hours (kWh) of electricity in February, 117 percent of average. The power plants are projected to generate 9.9 billion kilowatt hours during calendar year 2012. The long-term average is approximately 10 billion kilowatt hours.
To view the detailed three-week release forecast for the mainstem dams, go to: www.nwd-mr.usace.army.mil/rcc/reports/twout.html
Communicating with the basin
As part of efforts to communicate more frequently and more broadly with stakeholders in the Missouri River basin during 2012, the corps began holding twice monthly informational conference calls in January. The calls are geared toward Congressional delegations, Tribes, state, county and local officials and the media. Audio files of the call can be retrieved at: www.nwo.usace.army.mil/pa/2012Teleconference/pressconf_arch.html
The general format of each call includes an update from the National Oceanic and Atmospheric Administration’s Climate Prediction Center on the long-range temperature and precipitation outlooks for the Missouri River Basin. The Missouri River Basin Water Management Division follows with a report of the current basin conditions, forecast inflows, and current and forecast reservoir release plans. The corps’ Omaha and Kansas City Districts provide an update on the status of levee and other repairs following the flood of 2011. A question and answer opportunity follows the reports.
The public is also encouraged to continue following the corps on its social media sites to remain apprised of the most recent information and latest updates.
| Date Taken: | 03.06.2012 |
| Date Posted: | 03.06.2012 14:46 |
| Story ID: | 84819 |
| Location: | OMAHA, NEBRASKA, US |
| Web Views: | 88 |
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