The poorest of the city was left behind to drown. This was the plan. Forget the sanctimonious bullshit about the bullheaded people who wouldn't leave.
The evacuation plan was strictly laissez-faire. It depended on privately owned vehicles, and on having ready cash to fund an evacuation. The planners knew full well that the poor, who in new orleans are overwhelmingly black, wouldn't be able to get out. The resources -- meaning, the political will -- weren't there to get them out.
The email attributed to a rescue worker reads:
There are dead animals floating in the water, pets left behind.
The rescuers smell like gas when they come back in; there's gas in all of the water that consumes the area. Fires are burning all over the place.
Entire teams are working on nothing but evacuating the hospitals. All four of the major hospitals are beginning to flood. Critical patients have to get out or surely they will be lost. Generators cannot run forever; that's just the way it is. There are limited facilities to take those that are rescued and those that need to be evacuated. Anything that leaves by air leaves by helicopter. There are no runways for planes that aren't under water. Only one drivable way in and out.
Until they can do something about the three levees that are broken, more water will come and more water will kill. The water poses major health threats. Anyone with even a small open cut is prone to infection.
(more at link)