2011 Mississippi River floods During the 2011 floods, the Army Corps of Engineers decided to open the Morganza Spillway at 1/4 of its capacity to allow to enter the Morganza and Atchafalaya floodways. In addition to reducing the 2011 flood crest downstream, this reduced the chances of a channel change by reducing stress on the other elements of the control system. 2011 Mississippi River floods The Mississippi River floods in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway in the past century, comparable in extent to the major floods of 1927 and 1993. In April 2011,
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