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
120th Ohio Infantry May 1. Ordered to join Banks at Alexandria on Red River Expedition May 1. Embarked on steamer "City Belle". Action en route at Snaggy Point May 3. Over 200 men captured. Those who escaped were formed into a battalion of three companies and marched to Alexandria. Retreat from Alexandria to Morganza May 13–20. Mansura or Marksville Prairie May 16. Duty at Morganza until September. Expedition to mouth of White River and St. Charles September 13–20. Expedition to Duvall's Bluff, Ark., October 21–27. The regiment lost a total of 300 men during service; 2 officers and 17 enlisted men killed or