I was just thinking about that. Maybe that guy was just talking about the parish he was in?
I think CNN is talking about the area of heavy flooding up to the rooftops, where the rescues are taking place. The mayor is probably talking about any area that is flooded, even though much of the area visible in the afternoon copter shots apppeared to be street flooding of a few feet, many of them looked to be flooded just slightly above the foundation line, but well below the windows.