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 Little Western Olive Quills.
This is one of the most important species of the Baetidae family. It is distributed across the country but most of its fame comes from excellent hatches in the West. Prior to many other former species being combined with Baetis tricaudatus, most angling literature considered it the most populous and widespread western species of the Baetidae family.