Those levees are a job for the Army Corps of Engineers and the Seabees... not a bunch of random weekend warriors (no offense meant, but they're probably only going to be good for raw manpower).
Plus when our economy is going to slump some from having to deal with rising gas prices, it probably isn't smart to pull 200,000 people away from jobs that they're already doing.
Just thinking. Not that they would have a huge impact given the population of the country, but the localized damage especially in small areas would be enough to shake some consumer confidence.