If you look at old pictures of the beaches here on Galveston island there was a lot more sand then than there is today due to beach erosion.
In your case its due to the drought. Several of our lakes got extremely low in the summer of 2011. The remains of an old town previously underwater emerged in one area. Things are back to normal now for most though several dead trees are still causing problems. .
As someone who is studying geology, what I can tell you is that if the water level suddenly receeds far out, then run for your life because that could mean a tsunami is coming. Tsunamis are possible in lakes, too. Though in this instance, I don't think a tsunami is responsible being that I don't hear any sudden breaking news.