Bayous, bald cypress swamps, and marshes…
The Atchafalaya Basin, the surrounding plain of the river, is filled with bayous, bald cypress swamps, and marshes that give way to more brackish estuarine conditions and end in the Spartina grass marshes, near and at where it meets the Gulf of Mexico. It includes the Lower Atchafalaya River, Wax Lake Outlet, Atchafalaya Bay, and the Atchafalaya River and Bayous Chene, Boeuf, and Black navigation channel. See maps and photo views of the Atchafalaya Deltas centered on 29°26′30″N 91°25′00″W.
The Basin, which is susceptible to long periods of deep flooding, is sparsely inhabited. The Basin is about 20 miles (32 km) in width from east to west and 150 miles (240 km) in length. The Basin is the largest existing wetland in the United States with an area of 1,400,000 acres (5,700 km2) including the surrounding swamps outside of the levees that historically were connected to the Basin. The Basin contains nationally significant expanses of bottomland hardwoods, swamplands, bayous, and back-water lakes. The Basin’s thousands of acres of forest and farmland are home to the Louisiana black bear (Ursus americanus luteolus), which has been on the United States Fish and Wildlife Service threatened list since 1992.
The few roads that cross it follow the tops of levees. Interstate 10 crosses the basin on elevated pillars on a continuous 18.2 mile (29,290 m) bridge from Grosse Tete, Louisiana, to Henderson, Louisiana, near at the Whiskey River Pilot Channel at 30°21′50″N 91°38′00″W. The Atchafalaya National Wildlife Refuge was established in 1984 to improve plant communities for endangered and declining species of wildlife, waterfowl, migratory birds and alligators.
The Atchafalaya Basin, or Atchafalaya Swamp (/əˌtʃæfəˈlaɪə/; Louisiana French: L’Atchafalaya, [latʃafalaˈja]), is the largest wetland and swamp in the United States. Located in south central Louisiana, it is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge. The river stretches from near Simmesport in the north through parts of eight parishes to the Morgan City southern area.
The Atchafalaya is different among Louisiana basins because it has a growing delta system with wetlands that are almost stable. The basin contains about 70% forest habitat and about 30% marsh and open water. It contains the largest contiguous block of forested wetlands remaining (about 35%) in the lower Mississippi River valley and the largest block of floodplain forest in the United States.