I had ID'd this as Spring Azure, presumably using a western butterfly guide, but iNat is showing them as an eastern species only. Maybe there's been a taxonomic split? I'll do some more research and update with a species designation soon.
Not positive it isn't A. prostrata but A. calendula seems more likely to occur in Humboldt County.
This species is typically seen foraging on Beach Pea and willow during the spring and summer in these coastal dunes. Nests are in open sand near foraging areas. The nest terminates in a single cell as far as is known.