You might also find some information about the Sierra club law suit and envrionmental weenies stopping it.
I recall reading that they stood in the way of some sort of "flood gate" proposal; which would have been one part of a flood prevention system.
Enviro and local interests objected even to many of the ongoing minor upgrade and routine repair projects.
The honest enviros will admit that they advocate large parts of NOLA reverting to wetlands.