I have dove allatoona about a half dozen times. I dove in the summer usually off of McKinney Campground. There are alot of campsite that allow you to walk to the water. It is definitely the dead sea. The visibility was usually around 5 to 7 feet and cleared up a bit as you descended. Surprisingly, I didn't even find alot of trash. From what I recall, I only went about 20 feet deep and it was getting pretty cool (and dark) in a 3 mm. If I recall correctly, you had to carry a light below about 10 feet as it got real dark, but it has been almost a year since I dove that section. I will have to try again when my drysuit gets here. I have also dove off the swim beaches at McKinney. The swim beaches are a longer walk and you have to get pretty far out to get to 20 feet (and then you have to worry about boat traffic).
I do hear alot of people dive the Etowah river just downstream of the dam in Cartersville. Apparently there was an old bridge that they shoved off into the water. There is also an in-use bridge near the old bridge pilings that could make for interesting treasure hunting. I don't know the schedule, but I hear there are times when they aren't running the dam for power and the current is managable. There is a scuba shop in Cartersville that has people that dive the river on a regular basis.
