The updated 2023 calendar year runoff forecast for the Missouri River Basin above Sioux City, Iowa, continues to be below average.
January runoff in the Missouri River Basin above Sioux City was 1.1 million acre-feet, 134 percent of average.
Runoff was above average due to warmer-than-normal temperatures in the upper basin resulting in some snowmelt runoff.
Precipitation in January was below normal for most of the upper basin except for southern South Dakota, which saw above-normal precipitation. The 2023 calendar year runoff forecast above Sioux City is 21.1-million-acre feet, 82 percent of average.
The runoff forecast is based on current soil moisture conditions, plains snowpack, mountain snowpack, and long-term precipitation and temperature outlooks.
At the start of the 2023 runoff season, which typically begins around March 1, the total volume of water stored in the Missouri River Mainstem Reservoir System is expected to be 46.0 million-acre-feet, 10.1 million below the top of the carryover multiple-use zone.