There are important considerations when seeking such waters. Below is an excerpt from my Destination Theater's presentation at Pleasnton CA's 2019 Fly Fishing Show:
a) initially, the water temps are too cold and flows are too high
b) then, the flows are ideal, but water temps remain too cold
c) finally, flows and water temps are optimum for about 10 days ONLY
...then flow and temps are too low and warm!
if there's water , there are trout
Your first cast is the most productive for these opportunistic feeders
Above and below..."pan-size" or shall I say "hand-size" stream-bred trout
"OK, rise again..."