Corps Begins April With Ffull Capacity Of Flood Control Storage

Spring open house allows for public comment.

Published on: Apr 16, 2012

Unusually warm and dry conditions in the Missouri River basin during the month of March resulting 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.

Corps Begins April With Ffull Capacity Of Flood Control Storage
Corps Begins April With Ffull Capacity Of Flood Control Storage

"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 Master 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.     

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: 

Spring Public Meetings

The 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 spring meetings is as follows:

April 19,

*Jefferson City, Mo. Truman Hotel & Conference Center, 1510 Jefferson Street. Open House Noon, Public Meeting 1 p.m.

*St. Joseph, Mo. Stoney Creek Inn & Conference Center, 1201 Woodbine Road. Open House 6 p.m. Public Meeting 7 p.m.

April 20

*Sioux City, Iowa.  Stoney Creek Inn & Conference Center, 300 3rd Street. Open House 10 a.m. Public Meeting 11 a.m.

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 month 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 electricity 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:

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 seventh call of the year is scheduled for Friday, April 6. Calls are geared toward Congressional delegations, Tribes, state, county, local officials and the media.  Audio files of the call can be retrieved at: The call is also offered as a free podcast in iTunes. Subscribe at: Or, simply run a search for Missouri River Basin Water Management in iTunes.

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.

Source: U.S. Army Corps of Engineers