The answer was yes. Flies that were drifted in such places were able to wake up the waters with slashes and splashes.
After a morning of fishing I went back to the Honda for a snack. I had a nice hot coffee in the early morning and left it in the cup holder. What was left was cold but still tasted good with the peanut butter crackers. I scanned the map and found I could fish another area stream for an hour or so, well off I was.