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.
fishing now for about 55 years. neuropsychologist. especially interested in the behavior of the nymphs to improve my presentation. have recently gotten into czech and polish nymphing for which i purchased an 11' sage 6 wgt z axis and am getting a big kick out of it. i am very curious as to how you get your underwater photos; i was thinking about working out some sort of reverse periscope. jhw