This Skwala nymph still has a couple months left to go before hatching, but it's still a good representative of its species, which was extremely abundant in my sample for a stonefly of this size. It's obvious why the Yakima is known for its Skwala hatch.
These are often called Giant Water Scavenger Beetles.
These are a common sight on most trout streams, especially in the calm backwaters. They aren't regarded as significant to trout, although I have found them in occasional stomach samples.