Hi, Rob. I live in Martinez, which is actually might as well be Augusta for all puposes. I am not aware of any SC or GA shore diving, several divers do go to Lake Thurmond and the Savannah River though. I have not been to either this year.
Check with the local dive shops and you will find out more. The dive shop I use has quite a number of divers that go out to the lake and river on a regular basis. They also set up some trips to WPB, Ginnie Springs and liveaboard trips to the Bahamas. We are going to Cay Sal August 9-15th on a liveaboard and there is a trip to WPB for Labor Day weekend.
I also think SeaJay could maybe offer some sites to you. He knows a bit more about the coast areas.