Morganza Spillway of the Morganza Floodway closed. In March 1997, the river water flow at Baton Rouge reached () per second. However, the flow rate never reached the threshold of () per second for opening Morganza, and residents of Sicily Island, Louisiana, became angry that the spillway was not opened to prevent flooding in their homes. In March–April 2008, officials considered but declined to open the spillway gates. While the spillway gates remained closed then, flooding still occurred in part of the Morganza floodway when the Mississippi River crested higher than levees near the spillway. Local residents and National Guard troops attempted
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