"Why in the world is New Orleans below sea level to begin with?"

I was interested in this statement by Mike Tidwell, author of "Bayou Farewell: The Rich Life and Tragic Death of Louisiana's Cajun Coast," who appeared on "Meet the Press" today:

Why in the world is New Orleans below sea level to begin with? I think the media has sort of accepted it uncritically that this city is below sea level which is why we have this problem. Miami is not below sea level. New York's not below sea level. It's below sea level because of the levees. The levees stop the river from flooding and the river's what built the whole coast of Louisiana through 7,000 years of alluvial soil deposits. And if you stop that flooding, the other second natural phenomena in any delta region in the world is subsidence. That alluvial soil is fine, it compacts, it shrinks. That's why New Orleans is below sea level. That's why the whole coast of Louisiana is--the whole land platform is sinking. An area of land the size of Manhattan turns to water in south Louisiana every year even without hurricanes.

You can't just fix the levees in New Orleans. We now have to have a massive coastal restoration project where we get the water out of the Mississippi River in a controlled fashion toward the Barrier islands, restore the wetlands. If you don't commit to this plan which is this $14 billion, costs of the Big Dig in Boston, or two weeks of spending Iraq, you shouldn't fix a single window in New Orleans. You shouldn't pick up a single piece of debris because to do one without the other is to set the table for another nightmare.

I expect to hear a huge debate about these environmental realities. There will be people who just want to rebuild and people putting immense preconditions on rebuilding. Restore the wetlands? "Get the water out of the Mississippi River"? The mind boggles.