I fish for trout in a creek with similar features to what you described. I use dry flies and casts up or down stream depending on where I am. The casts send the fly almost but not quite out of sight. I'll cast and let it drift just a bit. As was suggested wear drab colors, stay low and aware of shadows and vibrations. I spend a great deal of time crouching and hugging rocks. Sometimes I'll wait five to ten minutes before I cast as my entrance to the stream or a particular pool has spooked the nearby fish. I make one or two casts per section as I move up. If I don't get a strike then I move on or wait - depending on where the next casts will be directed. It's slow going and requires patience. Those instances where I don't get a strike I consider a learning experience - remembering how and where to cast for next time. It requires a bit of precision but it pays off over time.