In 2005, there were extensive failures of the levees and flood walls protecting New Orleans, Louisiana and surrounding communities. Five investigations (three major and two minor) were conducted by civil engineers and other experts, in an attempt to identify the underlying reasons for the failure of the federal flood protection system designed and constructed by the US Army Corps of Enginneers. In total, the federal flood protection system protecting greater New Orleans failed in 53 places.
The Mississippi River-Gulf Outlet Canal ("MR-GO") breached its levees in approximately 20 places, flooding much of New Orleans East, most of Saint Bernard Parish and the East Bank of Plaquemines Parish. Major levee breaches within the city of New Orleans occurred on the 17th Street Canal, the London Avenue Canal, and the wide, navigable Industrial Canal. Approximately 80% of the city of New Orleans was flooded.
Three major breaches occurred on the Industrial Canal; one on the upper side near the junction with MR-GO, and two on the lower side along the Lower Ninth Ward, between Florida Avenue and Claiborne Avenue. The 17th Street Canal levee was breached on the lower (New Orleans West End) side inland from the Old Hammond Highway Bridge, and the London Avenue Canal breached in two places, on the upper side just back from Robert E. Lee Boulevard, and on the lower side a block in from the Mirabeau Avenue Bridge. Flooding from the breaches put the majority of the city under water for days, in many places for weeks.
In the aftermath of Hurricane Katrina, five investigation teams studied the failure of the hurricane protection system that led to the failures, and thus most of the flooding. All five studies basically agree on the mechanisms of levee failures, and all agree that the system designed and built by the US Army Corps of Engineers was a system in name only.