Mississippi flood of 1973 western tributaries such as the Missouri and Arkansas to form a final catastrophic high in June. The flood resulted in the largest volume of water to flow down the Mississippi since the Great Mississippi Flood of 1927. Both the Bonnet Carre Spillway and the Morganza Spillway were employed. The Bonnet Carre was fully opened between April 7 and June 14 for a record 75 days. The 1973 flood was the first time the Morganza Spillway was opened: from April 19 through June 13. At Memphis, Tennessee, the Mississippi was over flood stage for 63 days, more than that of the
Morganza Spillway 2011 event) had been opened by the Corps of Engineers. The Corps estimated the flow rate at . However, on May 25, new estimates from the U.S. Geologic Survey (USGS) described a much higher rate of , resulting in the closure of 3 bays by May 26, and additional closures by May 29, bringing the total to 11 bays with an estimated diversion rate of . The Corps continued to evaluate the flow and close additional bays as appropriate. By June 6, the number of open gates had been reduced to seven, and by June 8, only two gates were