Morganza Spillway Structure (ORCS), in use since 1963, where floodgates are routinely used to redirect the Mississippi's flow into the Atchafalaya River such that the volume of the two rivers is split 70%/30%, respectively, as measured at the latitude of Red River Landing. During the 1973 Mississippi flood, the ORCS was being damaged due to high flow rates, leading to the opening of the Morganza Spillway to help relieve this pressure. Subsequently, the nearby Old River Control Auxiliary Structure (ORCAS) was constructed, adding additional floodgates for use during major floods. The Morganza Spillway, about downriver from ORCS and ORCAS, is designed for
156th New York Volunteer Infantry to Baton Rouge, then to Donaldsonville, July 11-15, and duty there until August 15. At Baton Rouge until March 1864. Red River Campaign March 23-May 22. At Alexandria March 25-April 12. Cane River April 23-24. Construction of dam at Alexandria April 30-May 10. Actions at Alexandria May 2 and 9. Retreat to Morganza May 13-20. Mansura May 16. At Morganza until July. Expedition from Morganza to the Atchafalaya May 30-June 5. Atchafalaya River June 1. Moved to Fort Monroe, Va., then to Washington, D.C., July 5-29. Sheridan's Shenandoah Valley Campaign August 5-November 28. Third Battle of Winchester September 19. Fisher's