Well, it never was completely flooded. There are some homes that never remotely got close to flooding.
But it took the failure of other canals as late as a day later to complete the process. I forget the name of it, but last canal to fail was on the other side of the river from downtown.
Reported on other FR thread - don't have the link - that comedian Steve Harvey was being interviewed on one of the cable news channels - said he was with an old gentleman whose house was beside the place where the levee was breached (not sure which one) and that it was caused by a BARGE BREAKING LOOSE AND BREAKING THROUGH it. FWIW.