The pollution in the BSF mostly pre-dated it becoming a park. The geology of the soils (in this case lack of) dictates fish abundance of the BSF more so than past industrial practices. Very few trout opportunities on the TN side, more so in KY.
Doesn't matter where you are in the state, if you are not targeting trout you do not need a trout stamp. Obviously if only trout are in the area and you are using troutish type lures/tactics, you will have to explain that to the officer and/or judge.