There are certainly enough bugs to get a run started and as the run grows and fish die the insect populations will grow as well. But again, the rivers are far from sterile.



I too have fly fished many NW rivers and I love chasing the small native trout. But they are small because our western Washington streams lack the huge diversity of insect life found in the less acidic streams like the Yakima and a the famed river of Montana.
Years ago the WDFW made the Middle fork of the Snoqualmie C&R only with much fanfare and predictions that it would one day become a destination stream like the Madison. Never happened simply because the rive lack enough bugs to make lots of big healthy trout. Our local rivers are not sterile but they sure as heck won’t grow trout like the Madison, Bighole, etc. That’s why I am headed to Montana next week.