OMAHA, Neb. --
Drought conditions in the Missouri River Basin above Sioux City, Iowa, continued throughout the month of August. Per the Master Manual and the September 1 System storage check, winter releases from Gavins Point Dam will be 12,000 cubic feet per second (cfs), as part of the overall water conservation measures.
While the month of July brought some much-needed moisture to the Missouri River Basin, the month of August showed a return to the warm and dry conditions seen in the basin over the last two seasons. August runoff was 0.9 MAF, 62% of average above Sioux City, and 0.6 MAF or 49% of average above Gavins Point Dam. The portion of the basin that drains into Oahe Reservoir was particularly dry, only experiencing 10% of its average August runoff. The 2022 calendar year forecast for the upper Basin, updated on September 1, is 20.2 million acre-feet (MAF), 78% of average. Average annual runoff for the upper Basin is 25.8 MAF.
“Reservoir inflows in August were much lower than average. We expect below-average inflows into the System through the rest of 2022,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “Based on the storage in the system at the September 1 storage check, winter releases from Gavins Point will be 12,000 cfs for a second year in a row,” Remus added.
As of September 2, the total volume of water stored in the System was 50.2 MAF, which is 5.9 MAF below the base of the System’s flood control zone. System storage is expected to continue to decline through the fall. The updated reservoir studies indicate that the System storage is expected to be than 8.4 MAF below the base of flood control at the start of the 2022 runoff season.
According to the National Drought Mitigation Center, drought conditions in the basin have worsened over the past month. Seventy-four percent of the basin is experiencing abnormally dry or drought conditions, with 7% of that being extreme or exceptional drought. Northern Montana and southwestern Nebraska show exceptionally dry soil conditions. The September and seasonal drought outlooks show existing drought persisting and expanding in the basin through the end of November.
Gavins Point Dam releases will be set to provide navigation flow support at a level 500 cfs above minimum service at all four target locations (Sioux City, Omaha, Nebraska City, and Kansas City). Flow targets may be missed to conserve water if there is no commercial navigation in a given reach. Season support will end on November 28 at the mouth of the Missouri River.
Winter Release Rate
As per the criteria in the Master Manual, the winter release rate is determined based on the Sept. 1 System storage. Per the September 1 System storage, winter releases from Gavins Point Dam will be at the minimum rate of 12,000 cfs. In anticipation of the low winter releases, letter will be sent in early September to all water users below Gavins Point Dam making them aware of the planned releases, and encouraging them to assess the risk to their facilities.
Monthly Water Management Conference Calls
Water management calls include an update on the Missouri River mainstem reservoir system operations. The next call for 2022 will be held on Thursday, September 8. All calls are recorded in their entirety and are available to the public on our website at https://go.usa.gov/xARQv.
Fall Public Meetings
The Northwestern Division will host a series of public meeting the week of October 24-28. The date and locations of the meetings are shown below.
- October 24, Fort Peck, MT @ 11:30am MT – Fort Peck Interpretive Center
- October 24, Bismarck, ND @ 5:00pm CT – Bismarck State College
- October 25, Ft Pierre, Sd @ 10:00am CT – Casey Tibbs Conference Center
- October 25, Sioux City, IA @ 4:00pm CT – Betty Strong Encounter Center
- October 26, Smithville, MO @ 11:00am CT – Jerry Litton Visitor Center
- October 26, Nebraska City, NE @ 6:00pm CT - Steinhart Lodge
- October 27, St. Louis, MO @10:30am CT – VUE17
- Gavins Point Dam
- Average releases past month – 28,900 cfs
- Current release rate – 30,000 cfs (as of September 1)
- Forecast release rate – 30,000 cfs (month of September)
- End-of-August reservoir level – 1206.8 feet
- Forecast end-of-September reservoir level – 1207.5 feet
- Notes: Releases will be adjusted as necessary to meet all downstream navigation targets.
- Fort Randall Dam
- Average releases past month – 28,100 cfs
- End-of-August reservoir level – 1354.9 feet
- Forecast end-of-September reservoir level – 1353.7 feet
- Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point.
- Big Bend Dam
- Average releases past month – 28,800 cfs
- Forecast average release rate – 27,000 cfs
- Forecast reservoir level – 1420.4 feet
- Oahe Dam
- Average releases past month – 29,600 cfs
- Forecast average release rate – 27,000 cfs
- End-of-August reservoir level – 1596.0 feet
- Forecast end-of-September reservoir level – 1593.6 feet
- Garrison Dam
- Average releases past month – 21,100 cfs
- Current release rate – 21,000 cfs
- Forecast average release rate – reduce to 14,000 cfs by mid-September
- End-of-August reservoir level – 1835.6 feet
- Forecast end-of-September reservoir level – 1834.2 feet
- Fort Peck Dam
- Average releases past month – 7,800 cfs
- Current release rate – 7,800 cfs
- Forecast average release rate – reduce to 4,000 cfs by mid-September
- End-of-August reservoir level – 2221.0 feet
- Forecast end-of-September reservoir level – 2220.4 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 886 million kWh of electricity in August. Typical energy generation for August is 1,011 million kWh. The power plants are projected to generate 7.3 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh.
To view the detailed three-week release forecast for the mainstem dams, go to http://go.usa.gov/xVgWr.
MISSOURI RIVER MAINSTEM RESERVOIR DATA
Pool Elevation (feet above mean sea level) Water in Storage (1,000 acre-feet)
On August 31 Change in August On August 31 % of 1967-2020 Average Change in August
- Fort Peck 2221.1 -1.1 12,249 84 -222
- Garrison 1835.6 -2.4 17,175 96 -724
- Oahe 1596.0 -2.2 15,371 87 -651
- Big Bend 1420.7 -0.2 1,673 98 -12
- Fort Randall 1354.9 0.0 3,401 102 +8
- Gavins Point 1206.8 +0.6 345 88 +12
Total 50,214 90 -1,589
WATER RELEASES AND ENERGY GENERATION FOR AUGUST
Average Release in 1,000 cfs Releases in 1,000 acre-feet Generation in Million kWh
- Fort Peck 7.8 479 74
- Garrison 21.1 1,296 197
- Oahe 29.6 1,821 262
- Big Bend 28.8 1,773 97
- Fort Randall 28.1 1,727 181
- Gavins Point 28.9 1,778 73