Atchafalaya Bay (uh-CHA-fuh-lei-uh), arm of the Gulf of Mexico, S La., 15 mi/24 km S of Morgan City, at mouth of Atchafalaya R.; c.21 mi/34 km long NW-SE, 10 mi/16 km wide; 29°25'N 91°18'W. Point Chevreuil is at NW side of entrance; at SE side is Point Au Fer with shell reef extending c.10 mi/16 km NW. On the reef c.3 mi/5 km offshore is Eugene Isl., site of Point Au Fer Reef lighthouse. Four League Bay is an 11 mi/18 km-long SE extension of Atchafalaya Bay, with channel into gulf from SE end. Entire bay comprises the Atchafalaya Delta State Wildlife Area. A new delta is being formed in it by discharge through the Atchafalaya R. Salt mines in area.
