It turns out that where we stayed, at the Gold Rush Cabin in the Hocking Hills was an old, broken dam. I just researched it and found that it was a dam on the Blackjack Creek.
This is a picture of the Blackjack Creek Dam from 1929.
Here is a picture of it (at a slightly different angle) in 2010. It is broken now and not holding back any water.
Carved in the wall of the dam are the words, "Black Jack Club 1919-30." I'd love to learn more about this.
Todd is standing near the broken part of the dam.
This area would be underwater if the dam was still functional today. You can see the wall of the dam on the very left of this photo behind the tree.