Right now, the water is full of debris, sewage, gasoline, household and industrial chemicals and dead people. Anything this loathsome brew touches is contaminated, probably badly enough that you want some Haz Mat protection to be in or around it.

It's ninety degrees in the Big Easy. Stuff that gets wet grows mold. Everything that is damp or wet right now is growing mold. As the water goes down, the mold will spread. You cannot remove that amount of mold, nor seal it in.

I believe that any structure exposed to the water will have to be torn down and disposed of in a hazardous waste landfill. Between the toxic water and the mold, you will not be able to handle demolition like you normally would. This is asbestos removal times a billion.

Remember that about 20% of the city is dry. So there will continue to be a New Orleans unless the decay of the other 80% renders the dry portion uninhabitable.

Rebuilding New Orleans will be the largest engineering project of our time. We can do, but will we?