The 320-km/200-mi course of the lower Mississippi River, from its confluence with the Red River, 74 km/48 mi north of Baton Rouge, Louisiana, to its mouth in the Gulf of Mexico, 145 km/90 mi southeast of New Orleans. Distributaries A number of distributaries carry or can carry much of the discharge of the river, chief among them the Atchafalaya River, diverging from the Red River northwest of Baton Rouge; this may eventually become the mainstream because of the buildup of sediment at the current mouth. The Bayou Lafourche, diverging at Donaldsonville, below Baton Rouge, is another important distributary, and above New Orleans a floodway can divert high water east to Lake Pontchartrain. Flowing southeast through rich alluvial lowlands, wooded swamplands, and salt marshes, the mainstream of the river divides into several channels (passes) 117 km/73 mi below New Orleans – Main Pass, North Pass, Southeast Pass, South Pass, and Southwest Pass. Economic and environmental aspects The delta is…