Big Sioux River Flood Repairs & Timeline

In June 2024, heavy rainfall across Iowa, South Dakota, and Minnesota filled the Big Sioux River, causing record flooding and leading to damage throughout the Riverside neighborhood. More than 100 homes were affected. The City of Sioux City is now advancing long-term flood protection efforts. Grant funding has been awarded through the Iowa Homeland Security and Emergency Management Levee Improvement Program, and the Sioux City Council has approved the engineered plans for a permanent levee extension designed to reduce future flood risk in the Riverside neighborhood.

The project will extend the Big Sioux River left bank levee system north along River Drive, replacing the temporary sandbag levee that has traditionally been used during high water events. The new levee will run from Goldie Avenue to Beck Street. To make space for the levee extension, the City purchased and relocated three homes along River Drive. Those structures have now been demolished, allowing design work to move forward.

FUNDING
In 2025, a grant through the Iowa Homeland Security and Emergency Management Levee Improvement Program was awarded to provide financial assistance for this project to support the improvement for flood protection. The grant covers 50 percent of the project's design and construction costs, totaling approximately $865,000.

TIMELINE
Since this project involves improvements to an existing Army Corps of Engineers levee system, several detailed plan reviews and permits are required. The design and permitting phase is expected to be completed by Fall 2027. Construction is scheduled to begin shortly after and conclude in Spring 2028.

REPAIRS TO DATE
The City has already completed multiple repairs to improve the performance of the levee system and related infrastructure along the Big Sioux River. These include:

• Repairing Gate 1's gear and casting
• Clearing sediment from river outfalls following the 2024 flood
• Replacing the outlet at Council Oaks Drive and Riverside Boulevard (completed in 2022)
• Repairing Gate 5 and addressing erosion near Bourette Street
• Replacing the flap gate at River Drive and Dacotah
• Repairing or replacing Gate 4 at River Drive and Bois Street

CURRENT EFFORTS
Design work is underway to extend the levee approximately 1,000 feet upstream.

To facilitate this project, the City purchased 3 homes and demolished them for this extension. Staff are also currently working on plans to repair storm sewer pipe near the Riverside Pickleball Courts to be completed by the end of 2026. Additionally, the Utilities Department is in the process of purchasing an additional portable pump trailer to assist with controlling future flood waters.

BIG SIOUX RIVER LEVEE EXTENSION PROJECT LIMITS MAP