Old River Control Structure be opened in an emergency to relieve water levels and water-pressure stress on various levees and other flood-control structures, including the Old River Control Structure. The floodway can reduce stress by diverting additional water from the Mississippi into the Atchafalaya. The Morganza Floodway was never used before the construction of Old River Control Structure, and as of 2016 has been opened only twice for flood control since completion of the Old River Control Structure. Old River Control Structure The Old River Control Structure is a floodgate system in a branch of the Mississippi River in central Louisiana. It regulates the
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,