Drought Conditions Continue In Missouri River Basin

The month of September brought mixed results for precipitation across the Missouri River Basin. Portions of Montana, North and South Dakota, and Nebraska received above average rainfall, while the remainder of the upper basin and lower basin were below average. Overall, September runoff in the Missouri River Basin above Sioux City, Iowa, was 1.3 million acre-feet, 109 percent of the long-term average. The annual runoff forecast for the upper Missouri River Basin above Sioux City is 29.1 MAF, 113 percent of average and the same as last month’s forecast.

“Rainfall was above average in portions of the upper Missouri River Basin for the month of September,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.

“Runoff was above average or near average in every reach except Sioux City, which was below average,” Remus added.

Soil Moisture conditions have improved in parts of the basin, but much of the lower basin as well as parts of Montana and North and South Dakota remain abnormally dry. These drought conditions are expected to persist through the end of the year.

Total System storage as of Sept. 30 was 54.2 million acre-feet, which is 1.9 million acre-feet below the base of the 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 approximately 4.0 MAF below the base of flood control at the start of the 2024 runoff season.

Fort Peck Dam

Average releases past month – 7,400 cfs

Current release rate – 4,000 cfs

Forecast average release rate – 4,000 cfs

End-of-September reservoir level – 2228.8 feet

Forecast end-of-October reservoir level – 2229.0 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 919 million kWh of electricity in September. Typical energy generation for September is 900 million kWh. The power plants are projected to generate 7.9 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh.