Mississippi flood of 1973 The Morganza Spillway was opened, flooding portions of the Atchafalaya River basin in Louisiana and causing the deaths of thousands of head of livestock and white-tailed deer. The 1973 flood was notable for nearly causing the failure of the Old River Control Structure above the Mississippi River Delta, which would have sent the Mississippi's main channel flowing into the Atchafalaya River and bypassing most of the delta region including the major port of New Orleans, Louisiana. In spite of record high flows, flood stages were not as high as past events. Red River Landing, Louisiana reached 58.22 feet on May
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