Morganza Spillway enters the Morganza Floodway, which extends from the spillway at the Mississippi River south to the East Atchafalaya River levee. The floodway, long and wide, includes a stilling basin, an approach channel, an outlet channel, and two guide levees. From there, diverted water enters the Atchafalaya River Basin Floodway near Krotz Springs, Louisiana, and continues to the Gulf of Mexico. In an extreme flood event, a major release of water from the Morganza Spillway into the Morganza Floodway and Atchafalaya Basin inundates not only the floodways themselves (between their levees), but extensive additional areas of southern Louisiana throughout the Atchafalaya
Morganza Spillway still open. All bays were closed on July 7, 2011. The Corps had estimated that it would take opening one-fourth of the spillway’s 125 bays — or 31 bays — to control the flow of the river through Baton Rouge in response to a forecast crest of anticipated on Tuesday, May 17, 2011, which must remain below of water per second through Baton Rouge to ensure the integrity of the levee system. Since Morganza never operated above , the flooding in the Atchafalaya Basin was considerably lower than had been anticipated during the initial estimates of . By May 29,