Drought conditions continue to impact a large portion of the upper Missouri River Basin. While runoff in the Missouri River basin above Sioux City, Iowa during the month of August was slightly above normal (107 percent of normal), the calendar year runoff forecast remains below normal at 23.1 million acre feet (91 percent of normal).

“Reservoir levels at the upper three large reservoirs, Fort Peck, Garrison and Oahe, are 3 to 9 feet below their desired elevations,” said Mike Swenson, team leader in the Missouri River Basin Water Management office. The total volume of water stored in the Missouri River Mainstem Reservoir System at the end of August was 52.7 million acre feet (MAF). The base of the flood control and multiple use zone is 56.1 MAF.

Based on the September 1 storage check, drought conservation measures will again be implemented this winter. “Winter releases from Gavins Point will be at minimum levels, averaging near 12,000 cfs from December through February. Temporary increases above 12,000 cfs will be provided during periods of ice formation to keep water intakes along the lower river operational.” When the reservoir system is full, Gavins Point winter releases are generally scheduled near 17,000 cfs, or higher if flood water is being evacuated.

The Corps previously announced it is providing a full 8-month navigation season based on the July 1 storage check. Flow support for navigation during the second half of the season increased 3,000 cfs from the minimum service level provided in the first half of the season. Full service level is 6,000 cfs above the minimum service level. Minimum service flow support is generally sufficient to provide a navigation channel that is 8 feet deep by 200 feet wide, and full service flow support provides a navigation channel 9 feet deep and 300 feet wide.

“In early August, conditions were wet in the lower portion of the basin allowing us to reduce Gavins Point releases. However, dry conditions have returned and Gavins Point releases have gradually been increased to meet navigation targets,” said Swenson.

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.

Public Meetings

The Corps will hold its fall public meetings in five cities throughout the basin in early October to discuss the 2013-2014 Draft Annual Operating Plan for the Missouri River Mainstem System. The public meeting will include a presentation from the Corps regarding 2013 operations and plans for regulating the reservoir system in 2014 followed by a question and answer session.

The meeting schedule is as follows:

Tuesday, Oct. 8

Kansas City, Missouri, 1 p.m.

National Archives Building

400 W. Pershing Road

Nebraska City, Nebraska, 7 p.m.

Lewis and Clark Center

100 Valmont Drive

Wednesday, Oct. 9

Fort Peck, Montana, 7 p.m.

Fort Peck Interpretive Center

Lower Yellowstone Road

Thursday, Oct. 10

Bismarck, North Dakota, 11 a.m.

North Dakota Game and Fish

100 N. Bismarck Expressway

Pierre, South Dakota, 5 p.m.

Joe Foss Building

523 East Capitol Avenue

Reservoir Forecasts

Gavins Point releases ranged from 20,000 cfs to 32,000 cfs in August, averaging 24,500 cfs. The reservoir behind Gavins Point Dam ended August at elevation 1206.3 feet msl. The reservoir will gradually rise to its normal fall pool elevation of 1207.5 feet msl in September.

Fort Randall releases ranged from 18,000 cfs to 33,000 cfs during August, averaging 23,700 cfs. Fort Randall releases will be adjusted during September as necessary to maintain the desired elevation at Gavins Point. The reservoir ended August at elevation 1355.4 feet msl, up 0.9 feet during the month. The reservoir is expected to decrease nearly two feet this month, ending September near elevation 1353.5 feet msl. 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 releases averaged 22,000 cfs during the month of August. They are expected to average near 30,000 cfs this month. The reservoir will remain near its normal elevation of 1420 feet msl during September.

Oahe releases averaged 24,200 cfs during the month of August. Releases are expected to average near 30,000 cfs this month. The reservoir ended August at elevation 1601.5 feet msl, down 1.1 feet during the month. The reservoir is expected to drop more than 3 feet during the month of September.

Garrison releases average 19,200 cfs in August. Releases will remain at 19,000 cfs until mid-September and then be decreased to 13,000 cfs. Garrison ended August at elevation 1834.6 feet msl, down 1.5 feet from the end of July. It is expected to drop less than 1 foot during September.

Fort Peck releases averaged 8,000 cfs in August. Releases will remain at 8000 cfs until mid-September and then be reduced to 5,000 cfs. The reservoir ended August at elevation 2225.1 feet msl, down 1.1 feet from the previous month. The reservoir is forecast to drop less than 1 foot during September.

The forecast reservoir releases and elevations discussed above should not be assumed to be definitive. Additional precipitation or lack of precipitation in the basin could cause adjustments to the reservoir release rates.

The six mainstem power plants generated 774 million kilowatt hours (kWh) of electricity in August. Typical energy generation for the month of August is 1006 million kWh. The power plants are projected to generate 7.6 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 MAIN STEM RESERVOIR DATA

 WATER RELEASES AND ENERGY GENERATION FOR AUGUST