Runoff in the Missouri River Basin above Sioux City, Iowa for the month of September was just under 1.0 million acre feet (MAF), 84 percent of average.  The 2015 runoff forecast is 24.9 MAF, 98 percent of average.  Average annual runoff is 25.3 MAF. 

The total volume of water stored in the Mainstem Reservoir System is currently 59.3 MAF, occupying 3.2 MAF of the 16.3 MAF combined flood control storage zones. “System storage declined 1.0 MAF during September. Water that was captured in the reservoirs during the spring and summer is being released to serve navigation and other downstream purposes,” said Mike Swenson, team leader in the Missouri River Basin Water Management Division. “Our plan is to evacuate all water stored in the flood zones of the reservoirs prior to the start of next year’s runoff season, which typically begins around March 1.”

The U.S. Army Corps of Engineers (Corps) Missouri River Basin Water Management Division previously announced it is providing an 8-month navigation season with full service flow support based on the July 1 storage check.  Full service flow support is generally sufficient to provide a navigation channel that is 9 feet deep and 300 feet wide.  Flow support for navigation service at the mouth of the Missouri River will end on December 1.  The ending dates for flow support for the 2015 navigation season by location are indicated below: 

Based on the September 1 reservoir system storage, Gavins Point winter release will be at least 17,000 cfs.  The winter release may be increased slightly if flood water remains in storage after the navigation season.  Winter releases are normally near 17,000 cfs.

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.

Draft Annual Operating Plan (AOP) and Fall Public Meetings

The Corps released the draft Annual Operating Plan in late September; it is now available online at http://cdm16021.contentdm.oclc.org/cdm/ref/collection/p266001coll1/id/2945. 

Public comments are due by November 20 and can be submitted to Missouri.Water.Management@nwd02.usace.army.mil.

The Corps anticipates relatively normal runoff into the basin for the remainder of the 2015 calendar year and into early spring 2016.  As a result, the Corps expects system storage to be near the base of the annual flood control pool at the start of the 2016 runoff season.  “All scenarios in the draft AOP indicate full service flow support to start next year’s navigation season,” said Swenson.  “If runoff volumes in the upper basin are near normal, full service flow support would continue during the second half of the 2016 navigation season.”

Fall public meetings will be held in five cities throughout the basin during the last week of October to discuss the draft report and take comments on the proposed operating plan.  The public meetings will include a presentation from the Corps regarding 2015 operations and plans for regulating the reservoir system in 2016, followed by a question and answer session.

The public meetings will be conducted at the times and locations listed below.

Tuesday, Oct. 27 – Smithville, MO

• Start time:  11 a.m.
• Jerry Litton Visitor Center
• 16311 DD Hwy

Wednesday, Oct. 28 – Pierre, SD

• Start time:  11 a.m.
• Capitol Lake Visitor Center
• 500 E Capitol Ave.

Wednesday, Oct. 28 - Bismarck, ND

• Start time:  6 p.m.
• Bismarck Civic Center
• 315 South 5th Street

Thursday, Oct. 29 – Fort Peck, MT

• Start time:  9 a.m.
• Fort Peck Interpretative Center
• Lower Yellowstone Road

Thursday, Oct. 29 - Council Bluffs, IA

• Start time:  6 p.m.
• Western Historic Trails Center
• 3434 Richard Downing Ave

Reservoir Forecasts

Gavins Point Dam releases averaged 28,100 cfs in September.  October releases are expected to average 28,500 cfs, but will be adjusted if necessary to meet downstream navigation targets.  The reservoir behind Gavins Point Dam ended September at elevation 1207.4 feet.  It will remain near its normal seasonal pool elevation of 1207.5 feet in October.

Fort Randall Dam releases averaged 27,000 cfs in September.  Fort Randall releases will be adjusted as necessary to maintain the desired elevation at Gavins Point.  The reservoir ended September at elevation 1354.4 feet, down 2.4 feet during the month.  The reservoir is expected to end October near elevation 1345 feet.  The reservoir is normally drawn down to 1337.5 feet in the fall to provide space for winter hydropower generation at Oahe and Big Bend.  The annual drawdown will continue in November.

Big Bend Dam releases averaged 21,300 cfs during the month of September.  They are expected to average 14,900 cfs this month.  The reservoir will remain near its normal elevation of 1420 feet during October.

Oahe Dam releases averaged 23,800 cfs during the month of September.  Releases are expected to average 14,900 cfs this month.  The reservoir ended September at elevation 1611.2 feet, down 1.4 feet during the month.  The reservoir is expected to drop less than 1 foot during the month of October.

Garrison Dam releases were gradually reduced from 20,000 cfs to 13,000 cfs in mid-September, averaging 16,400 cfs for the month.  Releases will remain at 13,000 cfs through November.  Garrison ended September at elevation 1841.7 feet, down 0.9 feet from the end of August.  It is expected to drop 1 foot during October.

Fort Peck Dam releases were reduced from 8,000 cfs to 4,500 cfs in mid-September, averaging 6,200 cfs for the month.  Releases will remain near 4,500 cfs through November.  The reservoir ended September at elevation 2234.8 feet, down 0.5 feet from the previous month.  The reservoir is forecast to drop less than a foot during October. 

The forecast reservoir releases and elevations discussed above are not definitive.  Additional precipitation, lack of precipitation, or other circumstances could cause adjustments to the reservoir release rates.

The six mainstem power plants generated 729 million kilowatt hours (kWh) of electricity in September.  Typical energy generation for the month of September is 898 million kWh. The power plants are projected to generate 8.5 billion kWh of electricity this year, compared to the normal of 10 billion kWh. 

To view the detailed three-week release forecast for the mainstem dams, go to: https://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf     

MISSOURI RIVER MAINSTEM RESERVOIR DATA

WATER RELEASES AND ENERGY GENERATION FOR SEPTEMBER