The real serious part of the problem is actually NOT about the immediate damage the flood did, but the water that will NEVER go away naturally. It's a real tragic at the commerical lost, but who cares about oil when the death rate shall triple within a week because of the mentioned crime rate, and the following...
The flooded areas are all below sea level. This means that there is just absolutely no way (evaporation seriously doesn't count) for the water to naturally disappear. USA Government did send some pumps down there to get the water out, but how many pumps and how long will it take to get out all that water within an entire state? You got a huge pool of still water, with at least 60000 people trapped inside. Diseases will break out so easily in this situation. All the clean water is in ruin, so you lost water supply on top of diseases.
Assume that the government succeeded in rescuing all the people from the trap. You still got an entire state flooded with water. Even the workers there can be afflicted with those illness when they try to pump out that water. On TV here, I saw a helicopter with a tiny bucket trying to pump water out that way? Unless USA got some secret technology coming up, Louisana maybe flooded for a good old half a year if we're to wait for helicopters to clean up the flooding in such inefficient manner. Now let's make further assumption how USA miraculously got all the water out. You still got the street cleanup, and finishing off the diseases...
I know that Canada has already sent a technical support team to assist the rescue missions, but it's a massive 560,000 dollars to fund the team of 46 people for only 10 days, and that's assuming the 46 people will not share their clean water/food supplies with the victimes (which they definitely will do.)
On top of our prayers, USA will also need heavy financial fundings...
On the other hand, nobody mentioned Hurrican Emily that is even stronger than Hurrican Katrina, and smashed Mexico to pieces? Poor Mexico is in the same desperate need, just like the USA too... (but it's true that their water can flow away naturally though, unlike the below sea-level areas in the USA, yet still... pray for Mexico/that region too)