Lake Hartwell is near Clemson (Go Tigers!) and Anderson, South Carolina. It's a sizable Lake. There were several areas to the campground and there were about 120 spots, with electric and water.
We got our spot pretty last minute and we could see the lake across the road. It was not an amazing spot, but it wasn't a bad spot, especially considering our one neighbor never showed and left some room between spots.
Would definitely go back, though not in summer when it's hotter than hell in South Carolina.
Spring, fall and winter, only!
Some of the South Carolina state parks offer a winter special for camping. If you reserve a spot for 30 days they'll cut the price in half. Makes it pretty affordable. Only works for December January and February.
Good thing to ask about ahead of time!
In our area they still haven't dropped the price into off season rates! And the leaves are all of the trees and everything looks pretty bleak!