The Atchafalaya Swamp Basin is the largest overflow swamp in the US, covering over one million acres from Simmesport to Morgan City. Used for flood control, the basin consists of three floodways including the Morganza Floodway, West Atchafalaya Floodway & Atchafalaya Basin Floodway.
The basin includes over 173,000 acres of cypress swamps and 64,000 acres of aquatic habitat. Sixty percent of the basin is under the jurisdiction of the State Land Office, Department of Wildlife & Fisheries, the U.S. Fish & Wildlife Service and the US Corps of Engineers. The remaining forty percent is owned by private landowners.