A flood risk study for the Big Sioux River in the Sioux City metro area will soon proceed in a partnership of local and federal entities.
The June 2024 Big Sioux River flooding in the McCook Lake area of North Sioux City caused damage to more than 100 homes, and Interstate 29 was flooded for several days.
The study focuses on the Big Sioux in southeast South Dakota and northwest Iowa.
Union County, South Dakota first requested the study in 2025. The U.S. Army Corps of Engineers is partnering Union County, North Sioux City, Sioux City, and the Dakota Dunes Community Improvement District for the project, called the Lower Big Sioux River Flood Risk Management Study.
Jen Gitt, a U.S. Army Corps of Engineers official, said, “We are at the very beginning of that process. Community input will be an important part of helping us understand the problems and potential solutions.”
The first public open house will be held in North Sioux City in late October.
The existing flood control plan for the area was completed in 1981. A statement from the Corps of Engineers says it generally performed as intended, but the recent flood events highlighted the need for further evaluation.
