Lou Dolinar, who wrote that excellent Real Clear Politics piece on NO rescues, writes in an e-mail:

I’ve received some feedback that suggests my estimates of rescues in RCP may actually be on the low side. The Washington Post, for example, surveyed victims in Houston: “Four in 10 were rescued by the Coast Guard, the National Guard, police officers or firefighters.” We all know about the problems with random samples, and what they’re sample of, but with 125-200K evacuees, that survey puts us in the ballpark of 50K rescues rather easily.
There have been other Coast Guard press releases besides the one I quoted. Here’s one that AP picked up on Saturday that says there were 6,000 CG rescues. But a later release puts the number at more than 20K.
I also ignored volunteer efforts for the most part. You can get a pretty good idea about how these worked from a Wall St. Journal piece about an 11-man Exxon Mobile rescue team, in four boats, who have pulled in 1500 people. There were “dozens” of similar volunteer teams operating.
Oh, then there were those bad New Orleans cops who ran away.
I think this guy may have been more typical.