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
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