The average angler seldom catches lunker trout. It's not that these big trout aren't there, anglers see them chasing a lure or hitting insects.
Big trout remain even on heavily fished streams and rivers.
The challenge is outwitting these big trout and then landing them. To catch these larger trout the angler must fish differently. Using different techniques and changing where they fish is the secret. Look for big trout in the deepest pools or in undercuts or in areas where these trout can reach deep water as a retreat. The key here seems to be depth and on a small stream a 4 pool is deep enough to hold a lunker trout.