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Mississippi River Priority Site

Atchafalaya River, Louisiana


The Atchafalaya River is a distributary of the Mississippi and Red rivers; that is, it receives water from the two larger streams rather than emptying into them. From its confluence with the Mississippi, the Atchafalaya runs southward through Louisiana approximately 140 miles to the Gulf of Mexico.

Agricultural and forested lands occupy the northern end of the Atchafalaya's basin. On the southern end are marshlands and the river's forming delta at the Gulf. Between these two points lies the largest expanse of swamp wilderness on the North American continent, an area teeming with a globally significant diversity of life.

Without the U.S. Army Corps of Engineers' Old River Control Structure northwest of Baton Rouge, the Mississippi would likely change course and the Atchafalaya would become its main channel. As it is, the Corps, in response to the Great Flood of 1927 on the Mississippi, built a floodway through the heart of the Atchafalaya basin. Enclosed east and west by levees averaging about 15 miles apart, the floodway provides a diversionary route for high Mississippi waters to reach the Gulf, thereby reducing potential flood damages in the downstream urban areas of Baton Rouge and New Orleans.

Within the basin, the Louisiana Department of Wildlife and Fisheries manages 43,618 acres as one unit that includes the U.S. Fish and Wildlife Service's 15,220-acre Atchafalaya National Wildlife Refuge, the state's 11,780-acre Sherburne Wildlife Management Area and 16,618 acres owned by the U.S. Army Corps of Engineers.

The Corps has acquired 47,323 acres within the basin and has obtained land preservation and flood passage agreements with owners covering an additional 108,440 acres.

The Atchafalaya basin supports more than 200 species of birds, serving as key nesting territory for some and as a critical staging area for migrants crossing the Gulf of Mexico each spring and fall. It is also home to endangered species such as the Louisiana black bear, peregrine falcon and Bachman's warbler. Economically important harvests of crawfish and fish are produced from the basin, which shelters more than 85 fish species.

Strategies and Progress

Land use and river changes in the Atchafalaya and Mississippi river systems have resulted in a loss of the cypress and fisheries resources, a severe hypoxic (deficient in amount of oxygen) zone in the shallow waters of the Gulf of Mexico and profound rates of wetland loss along Louisiana's coast. And while The Nature Conservancy has been involved in coastal restoration for many years, hurricanes Katrina and Rita emphasized the increasing vulnerability of Louisiana's coast and economy to coastal wetland loss and compromised floodplains. We are now faced with an increased urgency to advance restoration of these systems. Our activities with partners align along three major strategies:

  • working with governments to secure and influence prioritization of public funds for ecosystem restoration;
  • promoting sound science and conservation planning to inform development and implementation of appropriate restoration strategies in the Atchafalaya and along the coast; and
  • reaching out to stakeholders including landowners, businesses and local governments to promote ecological understanding and conservation of the Atchafalaya basin and larger coast and create a vision for restoration success.

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