That is a plausable thought on how they got there. It is much more likely they were brought in by locals. Specifically boaters going to Chickamuga on Saturday and then fishing Cherokee Sunday or anyday in the next three weeks without doing a dissenfect on the boat used at Chickamauga. With all the lakes we have available, boaters are able to move through several bodies of water without a thought of what they are moving.
We live, we learn, we grow, when not trapped in our own little universe.