Most of this has been suggested above, but what should stand out as you search for them: Summer-run steelhead are amazing at finding hidden boulders, slots, and ledges in low water, and they're almost impossible to entice once you're lucky enough to find them. They'll stick to one good lie, usually hiding below turbulent water, for days or even weeks and then take full advantage of the slightest amount of rain to move on to their next holding spot. They tend to restrict their movements to pitch-dark nights, more so than winter-run fish. You may find them schooled up at the bottom of larger, bath-like pools when the water temps are up, but by then, their instinct to chase a fly or anything else that moves, has shut down completely. They are a really interesting, albeit elusive and frustrating fish for a fly fisherman.