If you really want to get an eye-opener of which lakes used to be trout lakes vs which ones are still trout lakes, get a copy of Ernie Wolcott's books "Lakes of (Eastern/Western) Washington and check out the old planting data. There is two volumes; Eastern and Western WA.

I was researching some old plant data on certain eastern WA lakes and was surprised to see the state used to stock them and even put Brook Trout in some of the hotter seep lakes.