CJ, as you stated with all the water quality factors affecting the survival of trout, the predator issue is another problem.
Like the big creek behind your camp the large pickerel can really take their toll.
The small stream that runs thru my property supports a self sustaining population of brook trout but it's mostly too small to allow other predators to grow large enough and only small PS's are any competition.
The term "it depends" really applies to trout.