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Big Sioux River Plan Under Scrutiny After 2024 Floods
16 Sep
Summary
- US Army Corps of Engineers and local governments are reevaluating the flood plan.
- McCook Lake community was devastated by 2024 flooding events.
- The study could take three years and cost up to $3 million.

Recent flooding events in 2024 have prompted a critical reevaluation of the existing flood-control plan for the lower Big Sioux River area. The U.S. Army Corps of Engineers has initiated a partnership with local governments, including Union County, the city of North Sioux City, and the Dakota Dunes Community Improvement District, to enhance protections for the region.
These efforts are particularly focused on safeguarding communities like McCook Lake, which suffered extensive damage during the 2024 flood. Heavy rainfall, totaling over 17 inches in some locations, led to record-high water levels on the Big Sioux River. A temporary levee, part of the historical flood plan, inadvertently diverted waters toward McCook Lake, causing it to overflow.
The consequences of this overflow were severe, with over 100 homes damaged and critical infrastructure destroyed. North Sioux City incurred millions in repair costs, and many residents faced significant losses, with some lacking adequate flood insurance or sufficient federal assistance.
The Corps acknowledges that while the existing plan "has generally performed as intended" historically, recent events "highlighted changing conditions and new challenges." A public open house is scheduled for late October in North Sioux City. This feasibility study is expected to last up to three years and involve a total cost of $3 million, with the Corps and local partners sharing expenses equally.