Morganza Spillway in 1954, the Morganza Spillway has been opened twice (in 1973 and 2011), and considered for opening during four other major floods of the Lower Mississippi River. On April 17, 1973, in order to lower the water level of the Mississippi River and relieve pressure on the Old River Control Structure, the Corps of Engineers opened 42 of the 125 steel gates of the Morganza Spillway for the first time since its completion, allowing about half of its maximum designed flowrate to pass from the Mississippi into the Atchafalaya Basin. The spillway received minor scouring and slight damage to the
114th Ohio Infantry River Campaign April 26-May 22. Graham's Plantation May 5. Retreat to Morganza May 13–20. Mansura, or Marksville Prairie, May 16. Expedition to Atchafalaya May 30-June 6. Duty at Morganza until November 21. Moved to mouth of White River, Ark., November 21–26. Return to Morganza December 6. Expedition to Morgan's Ferry, Atchafalaya River, December 13–14. Moved to Kenner, La., January 8, 1865; thence to Barrancas, Fla., January 24. Campaign against Mobile, Ala., and its Defenses, March 20-April 12. March from Pensacola, Fla., to Blakely, Ala., March 20-April 2. Occupation of Canoe Station March 27. Siege of Spanish Fort and Fort Blakely