Bayou Sauvage National Wildlife was authorized in 1986 and officially established in 1990. The refuge is located within the city limits of New Orleans and encompasses approximately 23, 000 acres. It is the largest urban National Wildlife refuge in the United States. The refuge is one of the last remaining marsh areas adjacent to Lakes Pontchartrain and Borgne. The refuge contains a wide variety of habitat including bottomland hardwoods, fresh and brackish water marshes, lagoons, canals, borrow pits, cheniers, and natural bayous. Most of the refuge is located within massive hurricane protection levees built to protect New Orleans East from storm surges and flooding, thusly a network of pumps and flapgates provide a way of regulating water levels seasonally to encourage the summer growth of emergent plants that in turn provide waterfowl food supplies in the winter.