West Atchafalaya Floodway and west by the Atchafalaya Basin protection levees, and on the south by the Gulf of Mexico. Farther downstream, floodwaters enter the Gulf of Mexico through the Atchafalaya River below Morgan City, Louisiana and the Wax Lake Outlet. West Atchafalaya Floodway The West Atchafalaya Floodway is a flood control structure of the Mississippi River and Tributaries Project located in the Lower Atchafalaya Basin in south-central Louisiana. It has a project design flood flow capacity of . The Atchafalaya Basin system comprises three floodways. Two of these, the West Atchafalaya Floodway and the Morganza Floodway, are at the northern end. Together
2011 Mississippi River floods to open more gates on the spillway, the Corps studied four flooding scenarios, all of which assumed the Bonnet Carré Spillway near New Orleans would be concurrently operating at full capacity (100%). Following this analysis, which showed that extensive flooding was expected in the Atchafalaya Basin regardless of the choice made regarding the Morganza Spillway, the Corps decided to start the 2011 diversion by opening the spillway a bit less than described in scenario 1a (21%, not 25%) The Corps of Engineers subsequently released a map showing the estimated times it would take the flood waters to reach the various