This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.
Described by Kondratieff, B.C. & Kirchner, R.F. (1991) New Nearctic Chloroperlidae (Plecoptera). Journal of the New York Entomological Society. Devoted to Entomology in General 99, 199–203.