section_path: History/Future
section_name: Future
paragraph_text: Future
  
  Geologists believe that the lower Mississippi could take a new course to the Gulf. Either of two new routes—through the Atchafalaya Basin or through Lake Pontchartrain —might become the Mississippi's main channel if flood-control structures are overtopped or heavily damaged during a severe flood.
  
  Failure of the Old River Control Structure, the Morganza Spillway, or nearby levees would likely re-route the main channel of the Mississippi through Louisiana's Atchafalaya Basin and down the Atchafalaya River to reach the Gulf of Mexico south of Morgan City in southern Louisiana. This route provides a more direct path to the Gulf of Mexico than the present Mississippi River channel through Baton Rouge and New Orleans. While the risk of such a diversion is present during any major flood event, such a change has so far been prevented by active human intervention involving the construction, maintenance, and operation of various levees, spillways, and other control structures by the U.S. Army Corps of Engineers.
  
  The Old River Control Structure, between the present Mississippi River channel and the Atchafalaya Basin, sits at the normal water elevation and is ordinarily used to divert 30% of the Mississippi flow to the Atchafalaya River. There is a steep drop here away from the Mississippi's main channel into the Atchafalaya Basin. If this facility were to fail during a major flood, there is a strong concern the water would scour and erode the river bottom enough to capture the Mississippi's main channel. The structure was nearly lost during the 1973 flood, but repairs and improvements were made after engineers studied the forces at play. In particular, the Corps of Engineers made many improvements and constructed additional facilities for routing water through the vicinity. These additional facilities give the Corps much more flexibility and potential flow capacity than they had in 1973, which further reduces the risk of a catastrophic failure in this area during other major floods, such as that of 2011.
  
  Because the Morganza Spillway is slightly higher and well back from the river, it is normally dry on both sides. Even if it failed at the crest during a severe flood, the floodwaters would have to erode to normal water levels before the Mississippi could permanently jump channel at this location. During the 2011 floods, the Corps of Engineers opened the Morganza Spillway to 1/4 of its capacity to allow 150,000 cubic feet per second (4,200 m /s) of water to flood the Morganza and Atchafalaya floodways and continue directly to the Gulf of Mexico, bypassing Baton Rouge and New Orleans. In addition to reducing the Mississippi River crest downstream, this diversion reduced the chances of a channel change by reducing stress on the other elements of the control system.
  
  Some geologists have noted that the possibility for course change into the Atchafalaya also exists in the area immediately north of the Old River Control Structure. Army Corps of Engineers geologist Fred Smith once stated, "The Mississippi wants to go west. 1973 was a forty-year flood. The big one lies out there somewhere—when the structures can't release all the floodwaters and the levee is going to have to give way. That is when the river's going to jump its banks and try to break through."
  
  Another possible course change for the Mississippi River is a diversion into Lake Pontchartrain near New Orleans. This route is controlled by the Bonnet Carré Spillway, built to reduce flooding in New Orleans. This spillway and an imperfect natural levee about 12–20 ft (3.7–6.1 m) high are all that prevents the Mississippi from taking a new, shorter course through Lake Pontchartrain to the Gulf of Mexico. Diversion of the Mississippi's main channel through Lake Pontchartrain would have consequences similar to an Atchafalaya diversion, but to a lesser extent, since the present river channel would remain in use past Baton Rouge and into the New Orleans area.