Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
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.
Frontoclypeal projections are about twice as long as wide (extending to anywhere from just before the margin of the frontoclypeus to well beyond it), conical (or curved), and protrude anteriorly from the surface of the frontoclypeus (Funk et al. 2008)
Femora with dense row of long, fine setae on posterior margin (McCafferty et al 2017)
McCafferty, W.P., Jacobus, L.M., Provonsha, A.V., and Wiersema, N.A. 2017. Chapter 2 (Ephemeroptera) of Larvae of the Southeastern USA Mayfly, Stonefly, and Caddisfly Species. Clemson University Public Service Publishing. 10-160.