With the season opening in a couple of weeks I took a drive up to the upper reachs if the N. Fork Yuba in N. Ca. to scout some spots to get back to before the summer onslought. I was checking water temps. as I went and it went from around 38 to 42 degree F. I know the optimal temp. for trout is up around 50 so I'm wondering if I would be just practicing to be fishing these waters at temps listed. I'll probably be fishing nymphs for the most part.