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 Nelson, C.R. & Baumann, R.W. (1990) New winter stoneflies (Plecoptera: Capniidae) from the coast range of California. The Pan-Pacific Entomologist 66, 301–306.