This is the gate on the Mississippi/Red River confluence that is the source of the Achafalaya River. At the moment it is flowing at nearly 600,000 CPS. This is as much as Morganza with all the bays open, and an order of magnitude more than Niagara Falls. During the flood of 1973, the water began to erode the banks and get under the supports of the structure. Had it been destabilized, it could have failed and let the bulk of the Mississippi flow down the Achafalaya. That would have catastrophic consequences down river during a flood event, and could prevent shipping on the lower Mississippi until enough flow could be restored to float barges safely. John McPhee wrote about this in his book, Control of Nature.
Fisk, Harold Norman. Geological investigation of the Atchafalaya Basin and the problem of Mississippi River diversion. Waterways Experiment Station, 1952. – This report predicted the capture of the Mississippi River main channel by the Atchafalaya River by the 1970s, resulting in the construction of the Old River Control Structure.
Kazmann, Raphael Gabriel, and David B Johnson. “If the Old River Control Structure Fails?” (1980). – This report analyzes the economic consequences of the Old River Control Structure failing. These include the end of shipping to the Gulf on the old channel and the loss of drinking and industrial water in New Orleans and up river as the saltwater backed up the river.
Ashley N. Cox Jasen L. Brown Robert D. Davinroy Jason Floyd Emily Rivera Ivan H. Nguyen, Mississippi River and Old River Control Complex Sedimentation Investigation And Hydraulic Sediment Response Model Study, (2011) – An in-depth look at the current capacity and geology of the Old River Control Complex, including extensive plates in the appendixes.
Corps, Old River Control, (2009) – Brief history and pictures of the ORCS