August runoff in the Missouri River Basin above Sioux City, Iowa, was 1.0 million acre feet (MAF), 76 percent of average, according to the U.S. Army Corps of Engineers. This marks the third consecutive month with below average runoff in the upper basin. The 2016 calendar year runoff forecast is 22.4 MAF, which is 89 percent of the historic average.

The total volume of water stored in the Mainstem Reservoir System on September 1 was 58.1 MAF, occupying 2.0 MAF of the 16.3 MAF combined flood control storage zones.  “Water that was captured in the reservoirs during the spring and summer is being released during the drier months to serve navigation, irrigation and other authorized purposes,” said Jody Farhat, chief of the Corps’ Missouri River Basin Water Management Division. 

System storage peaked on June 22 at 60.1 MAF, occupying 25 percent of the available flood storage. The Corps is providing a full 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.

Based on the September 1 system storage, Gavins Point Dam winter release will be at least 17,000 cfs. This release rate is generally sufficient to meet the needs of downstream water intakes during the winter, but may be increased slightly during periods of ice formation on the lower river.  Winter releases are normally near 17,000 cfs.

“Full service navigation support and normal winter releases should be sufficient to evacuate all water stored in the flood zones of the reservoirs prior to the start of next year’s runoff season,” said Farhat. ”However, releases will be adjusted as needed in response to changing basin conditions throughout the fall and winter.”

Draft Annual Operating Plan and Fall Public Meetings

In mid-September, the Corps will post the 2016-2017 Draft Annual Operating Plan (AOP) for the Missouri River Mainstem Reservoir System on its website at https://www.nwd.usace.army.mil/MRWM/Public-Meetings/. Fall public meetings will be held in five cities throughout the basin during the first week of October to discuss the draft report and take comments on the proposed AOP.  The comment period on the draft AOP will close on November 11.  The public meetings will include a presentation from the Corps regarding 2016 operations and plans for regulating the reservoir system in 2017, followed by a question and answer session.

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

Wednesday, Oct. 5 – Smithville, MO

Start time:  11 a.m. (CDT)

Jerry Litton Visitor Center

16311 DD Hwy

Wednesday, Oct. 5 – Council Bluffs, IA

Start time:  5 p.m. (CDT)

Western Historic Trails Center

3434 Richard Downing Ave.

Thursday, Oct. 6 – Pierre, SD

Start time:  11 a.m. (CDT)

Cultural Heritage Center

900 Governors Drive

Thursday, Oct. 6 – Bismarck, ND

Start time:  6 p.m. (CDT)

Bismarck State College, National Energy Center of Excellence (NECE), Bldg. 15, Rm 335

1200 Schafer Street

Friday, Oct. 7 – Fort Peck, MT

Start time:  10 a.m. (MDT)

Fort Peck Interpretative Center

Lower Yellowstone Rd.

Reservoir Forecasts

Gavins Point releases averaged 25,000 cubic feet per second (cfs) during August. Releases were reduced to 23,000 cfs in early September, and will be adjusted throughout the fall to meet navigation targets in reaches with commercial traffic. The Gavins Point reservoir ended August at elevation 1206.6 feet and will rise to near elevation 1207.5 feet during September.

Fort Randall Dam releases averaged 24,200 cfs in August. Releases were reduced slightly in early September in response to the reduction in Gavins Point releases, and will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point Dam, but no significant changes in releases are expected at this time. The reservoir ended August at elevation 1355.1 feet, falling 0.1 feet during the month. The reservoir is expected to end September near elevation 1353.5 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 October and November.

Big Bend Dam releases averaged 22,700 cfs in August.  Releases are expected to average 20,600 cfs this month. The reservoir will remain near its normal elevation of 1420.0 feet during September.

Oahe Dam releases averaged 24,500 cfs during August.  Releases are expected to average 20,800 cfs in September. The reservoir ended August at elevation 1610.5 feet, falling 1.1 feet during the month. The reservoir level is expected to fall approximately 1 foot during September.

Garrison Dam releases averaged 20,100 cfs during the month. Releases will be reduced from the current release rate of 20,000 cfs to the fall rate of 13,000 cfs starting around September 15. With this release reduction the river stage at Bismarck will drop approximately 1.5 to 2.0 feet.  Garrison reservoir ended August at elevation 1839.3 feet, falling 2.0 feet during the month. The reservoir level is expected to fall approximately 1 foot during September.

Fort Peck Dam releases averaged 8,000 cfs during August. Releases will be reduced from 8,000 cfs to 4,500 cfs starting around September 15. The reservoir ended August at elevation 2233.9 feet, down 1.2 feet during the month. The reservoir level is forecast to fall an additional 0.5 feet during September ending the month near elevation 2233.4 feet.

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 820 million kWh of electricity in August. Typical energy generation for August is 997 million kWh. The power plants are projected to generate 7.8 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 AUGUST