Jason over at Countercolumn got a letter that uses a simple number to illustrate just what a mammoth effort is involved in Katrina relief:

I tried to explain what a massive undertaking it is to move the National Guard into the Katrina affected area to my wife. I had very little success until I broke it down to one number. 8 pounds. It is a magic number. The planning weight for a gallon of water. Times two gallons per person per day minimum. Times 40,000 personnel for the National Guard to support itself. The number gets pretty staggering really quick. 320 tons a day. And that is just for the water.

Meanwhile Instapundit links up more evidence showing it wasn't just the feds who had structural problems.