Morganza Spillway emergency use to divert additional water from the Mississippi River into the Morganza floodway, which merges downstream with the Atchafalaya floodway before entering the Gulf. Diversion of water from the Mississippi's main channel has the effect of lowering water level in the Mississippi downstream of the spillway, helping to relieve stress on levees and other flood control structures both upstream and down. Besides controlling flooding in a given event, the system is also designed to prevent the Mississippi River from permanently altering course down the Atchafalaya River, bypassing Baton Rouge and New Orleans. Water that passes the Morganza Spillway first
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