Hmmm...

Did someone blast those levies?

From Diver finds explosives residue on ruptured levy pieces.:

Divers inspecting the ruptured levee walls surrounding New Orleans found something that piqued their interest: Burn marks on underwater debris chunks from the broken levee wall!

One diver, a member of the U.S. Army Corps of Engineers, saw the burn marks and knew immediately what caused them. When he surfaced and showed the evidence to his superior, the on-site Coordinator for FEMA stepped-in and said "You are not here to conduct an investigation as to why this rupture occurred, but only to determine how best to close it." The FEMA coordinator then threw the evidence back into the water and said "You will tell no one about this."

Would our government do that? If so, why?