What's the history of levees in New Orleans?
In the early 1700s, French settlers tried to control the Mississippi River by reinforcing natural levees that were created from deposited sediment. When a resident received a land grant along the river, that person was obligated to maintain his or her portion of the levee. These manmade levees often weren't effective when heavy flooding occurred.
A levee breach in 1859 flooded thousands of homes, which prompted Congress to enact legislation for building levees, draining lowlands and reclaiming swamplands in Orleans and Jefferson parishes. The levee system was damaged during the Civil War and the State Board of Levee Commissioners planned to pay for repairs, but the project wasn't completed. Congress created the Mississippi River Commission (MRC) in 1879 to replace the state board and, with help from the U.S. Army Corps of Engineers (ACE), combat flooding by building more levees. The groups believed the water contained within the levees would scour the bottom of the river, making it deeper. The first federal legislation to authorize levees for flood protection was the Flood Control Act of 1917. During the flood of 1927, local leaders decided to save New Orleans from additional flooding by blowing up parts of the Caernarvon levee in St. Bernard Parish, an action that prompted the Flood Control Act of 1928, which gave the ACE authority to design and build flood control projects along the Mississippi River.
After Hurricane Betsy, Congress passed the Flood Control Act of 1965, authorizing the Lake Pontchartrain and Vicinity Hurricane Protection Project. That resulted in construction of surge barriers along Lake Pontchartrain. In the 1980s, ACE oversaw construction of taller levees to replace surge barriers.
The levee breaches that followed Hurricane Katrina were on manmade canals and floodwalls built by ACE.
New Orleans now has a $14.5 billion Hurricane and Storm Damage Risk Reduction System, which is monitored by engineers and civic activists. This system includes higher and stronger levees, improved floodwalls, floodgates at the mouths of canals and upgraded pumps.