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
Battery A, 1st Missouri Light Artillery on Jackson, Miss., July 5–10. Siege of Jackson July 10–17. Ordered to New Orleans, La., August 6, then to Carrollton, and duty there until October. Western Louisiana Campaign October 3-November 30. Bayou Cortableaux October 21. Carrion Crow Bayou November 3. At New Iberia until December 17. Moved to New Orleans, then to Madisonville January 7, 1864. Red River Campaign May 2–20. Moved to Alexandria, La., May 2. Attached to Army of the West and Department of the Missouri. Retreat to Morganza May 13–20. Expedition from Morganza to the Atchafalaya River May 30-June 6. Moved to Carrollton June. Duty there and