Despite a wetter year in parts of the region, the runoff in the Missouri River Basin remains below average. Years of drought have left a lasting impact, and the system has yet to recover fully. Iowa depends on the Missouri River to the west and the Mississippi River to the east to move grain by barge to the Gulf of Mexico. Much of this flow is regulated by dams upstream from Sioux City.
The U.S. Army Corps of Engineers is forecasting runoff for the Missouri River upstream of Sioux City to reach 19.1 million acre-feet this year—about 74 percent of the long-term average. Mike Swenson, who leads the Missouri River Power Production Team, says reservoir levels remain low enough to handle the expected inflows. He notes that the dam system has ample capacity to store water at this point in the season.
Swenson says that of the three biggest reservoirs on the system—Fort Peck, Garrison, and Oahe—both Fort Peck and Oahe are still sitting well below flood control levels. Fort Peck is more than seven feet below that threshold, and Oahe is more than eight feet below.
Swenson says the Corps will spend the coming months carefully managing releases to help balance water levels across the system’s three largest reservoirs. The goal is to bring Fort Peck, Garrison, and Oahe into better alignment ahead of next year’s runoff season. He says this kind of long-term planning is key to making sure the system is ready for whatever conditions the spring might bring.
The current runoff forecast is shaped by a mix of factors, including soil moisture levels, remaining mountain snowpack, and long-range outlooks for precipitation and temperature. While the system is still recovering from years of drought, Corps officials say they are closely monitoring conditions and adjusting as needed. With no immediate flood risk, the focus remains on carefully managing the reservoirs to be ready for whatever next year may bring.
