Levee failure: There was no backup plan.

If emergency managers had included levee breaches in their contingency planning for a New Orleans hurricane, could much of the city have been spared and lives saved?
"Hindsight certainly says that the Corps could have done a better job if they had taken steps to move material to adjacent areas or just close in so that if they had a problem like this then they could have moved quickly," said W.F. "Bill" Marcuson, president-elect of the American Society of Civil Engineers.
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President Bush and officials at the Federal Emergency Management Agency and even some in the Corps have suggested a breach of New Orleans' levees was unforeseen. But experts inside and outside New Orleans have said for years that a powerful hurricane could send water surging over the city's flood walls and earthen berms, and that could cause a breach.