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.
This is actually a specimen of the family Taeniopterygidae, probably Taenionema atlanticum. Notice the large sternal plate at the apex of the abdomen. This plate is used in drumming behavior. Adult Taeniopterygids mimic the sounds of male Ruffed Grouse in an attempt to draw in female grouse to parasitize. They attach themselves at the base of the beak and feed until gorged. They then mate, smoke a cigarette, lay some eggs, and die. On a serious note, all Taeniopterygids except species of Taeniopteryx, have the drumming plate. Nemourids are lacking this feature. There is a difference in the second tarsal segment as well. Happy Bugging!