Try this Google search on for size: "largest civil engineering disaster".
Robert Bea, a University of California, Berkeley professor who led a National Science Foundation investigation of the levee failures, said the mistakes made by the engineers on the project were hard to accept because the project was so "straightforward."
"It's hard to understand, because it seemed so simple, and because the failure has become so large," Bea said.
"This is the largest civil engineering disaster in the history of the United States. Nothing has come close to the $300 billion in damages and half-million people out of their homes and the lives lost," he said. "Nothing this big has ever happened before in civil engineering."