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Nebraska City News-Press - Nebraska City, NE
  • Drought persists across northern states; reservoir levels below normal

  • Despite wetter-than-normal conditions across much of the Missouri River basin during May, drought persists across much of the region and mainstem reservoir levels remain below normal.
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  • Despite wetter-than-normal conditions across much of the Missouri River basin during May, drought persists across much of the region and mainstem reservoir levels remain below normal.

    "Even though rainfall was two to three times normal in eastern Montana, and western North Dakota during May, runoff in the upper basin was only slightly above normal," said Jody Farhat, Chief of the Missouri River Water Management Division."The basin continues to recover from the 2012 drought and reservoir levels in Fort Peck, Garrison and Oahe remain 6 to 9 feet below the desired operating levels."

    Runoff into the Missouri River basin above Sioux City, Iowa for the month of May was 106 percent of normal.Based on the current soil moisture and mountain snowpack conditions, the 2013 runoff forecast inched to 21.3 million acre-feet, 84 percent of normal."The above normal rainfall improved soil moisture conditions, but did not eliminate drought in the basin," said Farhat.

    Heavy rain also fell across much of the lower basin resulting in increased flows on many of the tributaries below the system of reservoirs."Gavins Point releases were reduced from 24,000 cubic feet per second (cfs) to 12,000 cfs in late May and early June as part of our normal flood risk reduction measures," said Farhat."Thunderstorms can cause localized flooding even during droughts, so flood risk reduction remains a primary consideration as we progress through 2013."

    The Corps will continue to monitor basin conditions and fine tune the regulation of the reservoir system based on the most up-to-date information.
    "Reductions in releases for flood risk reduction also allow us to conserve water in the reservoirs," she added.

    As part of the Corps’ drought conservation measures, minimum service flow support is being provided for the first part of the navigation season, which runs through the end of June. Releases out of Gavins Point Dam are expected to increase to 23,000 cfs and average that level through the end of the month. The level of flow support for the second half of the navigation season and the season length will be determined following the system storage check on July 1. "Our latest forecast shows a slight improvement to the navigation service level is possible for the second half of the navigation season as well as a full 8-month season," said Farhat.   

    Minimum-service flow targets range from 25,000 cfs at Sioux City, Iowa to 35,000 cfs at Kansas City, Missouri.Minimum service flow support is generally sufficient to provide a navigation channel that is 8 feet deep by 200 feet wide although challenges may exist in localized reaches.
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    Gavins Point releases during the winter of 2013-2014 are forecast to be at the minimum rate of 12,000 cfs.Reduced support to navigation and low winter releases are the two primary drought conservation measures used to regulate the mainstem reservoir system.These measures help ensure the reservoir system can continue to serve the authorized purposes during an extended period of drought.

    According to information from the Natural Resources Conservation Service, the mountain snowpack peaked in both the reach above Fort Peck and the reach from Fort Peck to Garrison at about 95 percent of normal.Approximately 25 percent of the peak snow accumulation remains in the mountains.

    View mountain snowpack graphic here: http://www.nwd-mr.usace.army.mil/rcc/reports/snow.pdf

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