While I was up at Hopland for a Carabid workshop run by Kip Will of UC Berkeley, we went to a pond and saw lots of these Tabanids flying around the low vegetation near the water. They didn't seem interested in biting, but had other things on their minds; this photo is of a mating pair that landed on the vest of one of our group.

Kip later told me that Robert Lane had IDed them as Chrysops hirsuticallus on the basis of the photos. He's an emeritus UC Berkeley entomology professor, and this species was the subject of his Ph.D. thesis back in 1974. The following photos are not of the same specimens shown here, but of another that I captured at the time; I'm confident that it's the same species.

I submitted this to the genus-level page because I didn't see a page for C. hirsuticallus and didn't know how to create one.