Liquidfaction? Just my guess being that they were earthen levees.
Wolf Blitzer starting in on the meme that the war in Iraq has depleted National Guard resources. I expect to hear this ad nauseum over the coming weeks.
Is it possible that the river is now feeding into the lake? If that were the case, water would continue to flow into NO, without the lake rising.
I don't know if this is possible or not, just occurred to me.
I'm fairly sure that's the case with most levees in the area. Along the MS, except for the downtown area. The one levee they are showing where the big breech is is actually concrete. But, you're right, most are earthen.