Stonefly, Calineuria californica, family Perlidae. From the experts at BugGuide:

CA has a limited number of large perlid species (5). Of those, this looks most like Calineuria californica. In particular, the
yellowish median stripe on the pronotum and the reddish area over the ocellar triangle are consistent with this species.

Calineuria californica is the only Nearctic representative of the genus, and the species is also recorded for Santa Clara
County. Collection records can help to confirm the presence of a species, but they do not necessarily indicate the
absence of others. Pteronarcys californica would have a darker color, longer abdomen, shorter cerci, angular corners on
the pronotum and a netlike series of crossveins in the anal region of the forewing (the area closest to the wing bases).

Q: Is this a female? A: Unless a female is carrying an egg ball or its size can be compared to males of the same species, determining the
gender of adult stoneflies from photographs usually requires a clear view of the last few segments of the abdomen. Although most female
stoneflies are significantly larger than males, I'm not sure what your size estimate is measuring. A head-to-wingtip measurement is something
of an informal convention for adult stoneflies. Measured that way, the C. californica females probably would not be more than about 30-35mm.