Importing labor from the former USSR

Just a few weeks ago a guy in my Russian class was commenting that every lifeguard he'd talked to so far this summer was from one of the former Soviet republics - and here's proof! Only in the DC suburbs would you need to import workers from Russia to fill the quintessential teen summer job - don't kids work anymore? And for that matter, aren't there any other locals who would want those jobs?
Clearly, the answer is no, and I see two possible explanations, both of which could very well be true. The first is that there really is a labor shortage in this country (or at least a shortage of unskilled labor) - sorry Lou Dobbs. But even if that's true, why aren't those jobs being taken by the immigrants who are already there?
Like I mentioned earlier, in the American consciousness (or at least in Suburbia) lifeguards are supposed to be white teenagers or young adults. If the ones who are already in the community don't want those jobs, Russia, Moldova and Ukraine seem like great places to get them from. And $7 an hour plus housing seems like fortune to them, even if those wages are in increasingly worthless dollars. This is just a theory though, would love to hear others' thoughts on that.