Q: must be a LAKE...thanx so muchh
A: The true source of Atlanta water is actually the chattahoochee river because Lake Lanier is really just a very very large "puddle" of it. But that's being brainy, the practical answer is Lake Lanier. Atlanta's water totally depends on a very small area northeast of the lake getting rain. I also recommend reading reading "song of the chattahoochee" by sidney lanier its a great poem dicussing the path of the river.