Dry Conditions Return To Missouri River Basin In August
Earlier optimism about improving runoff in the Missouri River basin proved short-lived, as August brought a return to drought conditions. The Corps of Engineers announced September 7 that winter releases from Gavins Point Dam will be just 12,000 cfs., as part of overall water conservation measures called for in the Corps’ Master Manual for Missouri River operations.
“Reservoir inflows in August were much lower than average,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “We expect below-average inflows into the system through the rest of 2022. 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.”
While 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, the Corps said. August runoff was 0.9 million acre-feet (maf.), 62 percent of average above Sioux City, and 0.6 maf. or 49 percent of average above Gavins Point Dam. The portion of the basin that drains into Oahe Reservoir was particularly dry, only experiencing 10 percent of its average August runoff.
The drought is reflected in the power produced by the six hydropower plants along the mainstem of the river. The plants generated 886 million kWh of electricity last month; 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.
The 2022 calendar year forecast for the upper basin, updated on September 1, is 20.2 maf., 78 percent of average. Average annual runoff for the upper basin is 25.8 maf.
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 the flood control zone 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, the Corps said. Seventy-four percent of the basin is experiencing abnormally dry or drought conditions, with 7 percent 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.
As a result, the Corps will set Gavins Point Dam releases 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, the Corps said.
Season support will end on November 28 at the mouth of the Missouri River.
Fall Public Meetings
The Northwestern Engineer Division will host a series of public meetings the week of October 24-28 to discuss current conditions and planned reservoir operations for 2023. The date and locations of the meetings are as follows:
• October 24, 11:30 a.m., Fort Peck Interpretive Center, Fort Peck, Mont.
• October 24, 5 p.m., Bismarck State College, Bismarck, N.D.
• October 25, 10 a.m., Casey Tibbs Conference Center, Ft. Pierre, S.D.
• October 25, 4 p.m., Betty Strong Encounter Center, Sioux City, Iowa.
• October 26, 11 a.m., Jerry Litton Visitor Center, Smithville, Mo.
• October 26, 6 p.m., Steinhart Lodge, Nebraska City, Neb.
• October 27, 10:30 a.m., VUE17, St. Louis, Mo.
For more information, visit www.nwd.usace.army.mil/MRWM/Public-Meetings/.