Annual flooding in the Atchafalaya Basin created ideal crawfish habitat, and although most of Louisiana's crawfish production now comes from farms, the Basin still leads in wild-caught crawfish. The Atchafalaya Basin is one of the world's most extensive river-floodplain systems and an important floodway made up of the West Atchafalaya Floodway, the Morganza Floodway, and the Lower Atchafalaya Floodway, with levees directing Mississippi River water through the Basin to the Gulf of Mexico. The system regulates the combined flow of the Red and Mississippi rivers down the Atchafalaya River at the Old River Control Structure near Simmesport and was designed to handle half of the Project Design Flood, the maximum probable Mississippi River flood. The levees around the Lower Atchafalaya Floodway, built shortly after the Mississippi River Flood of 1927 and about 15 miles apart, permanently changed the Basin. Before their construction, a handful of year-round communities were scattered through the area and residents lived from its abundant resources. Afterward, communities within the floodway faced higher and more frequent floods, and most residents eventually moved outside the levees to places such as Henderson along the Basin's western edge. Many who had relied on subsistence hunting, fishing, and trapping had to turn to different work after moving to higher ground, while the annually flooded swamps and Basin helped make the region central to the growth of the commercial crawfish industry, with Henderson residents playing a vital role in bringing wild-caught crawfish to market. Though few people now live within its levees, the Basin remains a biodiverse wetland, a source of livelihood for fishermen and hunters, and a recreation destination. It contains the largest block of forested wetlands in the lower Mississippi River valley, the largest block of coastal cypress forest in the U.S., and habitat for more than 85 fish species and almost 300 species of resident and migratory birds. Sustaining the area remains difficult because of hydrology effects, sedimentation, invasive species, resource extraction, and development, requiring a delicate balance between protecting populations and preserving this vital landscape.