We will release him later today. I was only worried about him being eaten by predators but definitely mother nature will be better for him than a 10g tank with my 4 year old daughter wanting to constantly pull him out of the tank.
I would let him go, in as near to the exact same spot as you found him as possible. If you want a pet turtle, buy a Stinkpot, that only gets a few inches big, from a captive breeder. They run about $15.
Kristina