In the case of Katrina, the Army Corps of Engineers wanted to build levees capable of protecting the city against a Category 5 storm, and worked up a plan to do so. But the environmentalists, allegedly concerned about protecting species, stopped the city from building any levees capable of handling anything above a Category 3.
Katrina was Category 5.
Katrina was a Cat 3 hurricane when it hit New Orleans. It was a cat 5, but weakened before hitting the US coast.
Exactly my point.