Old River Control Structure channel and lock were also part of the original facility design. Subsequent expansion created what is now known as the Old River Control Complex, when the Auxiliary Structure, which became operational in 1986, was added to reduce pressure on the original floodgates after extensive damage caused by the flood of 1973. The Sidney A. Murray Jr. Hydroelectric Station, completed in 1990, also provides an additional measure of control at the site. Water from the Mississippi is normally diverted into the Atchafalaya Basin only at Old River, where floodgates are routinely used to redirect the Mississippi's flow into the Atchafalaya River
6th Missouri Volunteer Cavalry May 18-July 4. Assaults on Vicksburg May 19 and 22. Mason's Ford. Big Black River, June 9. Advance on Jackson, Miss., July 4–10. Near Baker's Creek July 7. Bolton's Station July 8 (detachment). Near Clinton July 8 (detachment). Near Jackson and near Clinton July 9 (detachment). Siege of Jackson July 10–17. Brookhaven July 18 (detachment). Near Morganza, La., September 8. Atchafalaya September 8–9. Hornersville, Mo., September 20 (2nd Battalion). Sterling's Farm, on Bayou Fordoche, near Morganza, September 27. Western Louisiana Campaign October 3-November 30. Reconnaissance toward Opelousas October 20. Opelousas, Barre Landing, October 21. Washington October 24. Bayou Bourbeaux November