Rhyacophila weitchpec sp. nov. is described from males collected in Humboldt Co., California. The new species is most similar to R. darbyi Fields 1981. The Rhyacophila viquaea Milne 1936 species group is reviewed and a trait table for separation of R. viquaea group males is presented. Rhyacophila balosa Denning 1989 is proposed as a junior synonym of R. lineata Denning 1956.