The U.S. Army Corps of Engineers’ flexible approach to water releases out of the Missouri River Mainstem Reservoir System during December and January has created an additional 500,000 acre-feet of flood control storage available for the 2012 runoff season.
In response to public concerns about the risk of flooding in 2012 and the fact that many repairs will not be completed prior to the start of the runoff season, the Corps evacuated additional water from the res ervoir system.
“The warmer temperatures we’ve seen this winter provided us with a lot of flexibility,” said Jody Farhat, Chief of the Missouri River Water Management Division. “As promised, we have taken advantage of those warmer temperatures to move additional water out of the system and create more flood control storage.”
The total volume of water stored in the reservoir system currently sits at 56.3 million acre feet, 500,000 acre feet below the base of the annual flood control zone. If temperatures are seasonal during the month of February, the Corps expects to evacuate an additional 100,000 acre feet of water; however warmer than normal temperatures will bring an early start to the runoff season and reservoirs could begin to rise during the month.
January runoff above normal
Warmer than normal temperatures throughout the basin in the first half of January inhibited ice formation and allowed the rivers to flow freel y resulting in above average runoff. Runoff into the system during January totaled 0.98 MAF, 131 percent of normal above Sioux City, Iowa. Mid-month, the first major blast of arctic weather moved into the basin causing many rivers to freeze over, temporarily reducing inflows to the reservoir system. This typically occurs during December, but was delayed this year due to the unseasonably warm temperatures. The water lost to river ice formation during the winter shows up in the spring as inflow when the ice melts.
Throughout the month of January, the Corps maintained releases from Gavins Point dam at 22,000 cfs, about 5,000 cfs higher than typical winter release rates. Warmer temperatures and the lack of river ice below the reservoir system created favorable conditions for maintaining releases to increase the amount of flood control storage in the system. Releases will be held at 22,000 cfs through the end of February barring ice-related concerns.
“So far this year, mountain snowpack has continued to accumulate at slightly below normal rates. However, we still have a few months of winter to get through so we will continue to monitor the weather and make adjustments to our release schedule if necessary,” said Farhat.
Traditionally, 61 percent of the peak mountain snowpack accumulation has occurred by Feb. 1. Mountain snowpack above Fort Peck is currently below normal at 87 percent of average. In the reach between Fort Peck and Garrison, mountain snowpack is tracking at 96 percent of average.
In contrast to last year, precipitation has remained below normal over most of the basin during the first half of winter. This, along with the warmer-than-normal temperatures, has resulted in a minimal amount of plains snow accumulation on the northern plains.
View mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf
View plains snowpack graphic/comparison to last year here: http://www.nwo.usace.army.mil/pdfs/SnowpackComparison2012v2011.pdf
The runoff for the 2012 calendar year is currently forecast to total 25.6 MAF, just above normal, historical runoff of 24.8 MAF. Runoff for the 2011 calendar year totaled 61.2 MAF, 247 percent of normal and the highest amount in the Corps’ 114 years of detailed record keeping.
Following last year’s record breaking runoff season, Beth Freeman, regional administrator for FEMA Region VII, reminds citizens within the basin to co nsider 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
Gavins Point releases averaged 21,900 cfs in January. Releases will remain near 22,000 cfs in February. The reservoir is currently near elevation 1207 feet above mean sea level. It will be lowered to 1206 by the end of February.
Fort Randall releases averaged 20,100 cfs during the month of January. Releases in February will range from 16,000 to 20,000 cfs as necessary to lower Gavins Point reservoir. The reservoir ended the month at elevation 1346.1 feet, an increase of 8.1 feet as part of its normal winter refill. The reservoir will continue to rise during February ending the month near elevation 1350. The reservoir is drawn down each fall to make room for increased releases at the upstream dams for winter hydropower generation.
Big Bend releases averaged 25,200 cfs in January. They are expected to average 22,600 cfs during the month of February. The reservoir will remain near its normal elevation of 1420 feet during the month.
Oahe releases averaged 26,700 during the month of January. The reservoir ended the month at elevation 1605.1, down 1.4 feet from the previous month. It is expected to end February near ele vation 1605.2 feet, 2.3 feet below the base of the annual flood control pool.
Garrison releases averaged 21,300 cfs in January. Releases were reduced from 23,000 to 20,000 cfs early in the month prior to freeze-in of the river. Releases were gradually increased to 22,000 cfs after the river conditions stabilized. Releases will remain at 22,000 cfs in February. The reservoir ended January at elevation 1838.2 feet, down 1 foot from December. The reservoir is forecast to end February at elevation 1837.5 feet, the base of its annual flood control pool.
Fort Peck releases averaged 11,800 cfs during January. Releases will remain at 12,000 cfs until mid-February and then be reduced to 11,000 cfs. The reservoir ended the month at elevation 2234.8 feet, down 1.4 feet from the previous month. It is expected to end February at the base of the annual flood control pool at 2234 feet.
The reservoir releases and elev ations 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 844 million kilowatt hours (kWh) of electricity in January, 119 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: http://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 tw ice monthly informational conference calls in Janauary. 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: http://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 (CPC) 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 an d 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.