Santa Clara Depot

Yeah, I think he means the Pacific Coast Ry also, the one that served basically the same area as the Santa Maria Valley.
The Santa Clara Station was built by and for the San Francisco and San Jose Railroad, not the SPC. It predates the SPC by many years. The SPC line actually passed to the south-west, near the current alignment of The Alameda.
I'm not sure if any SPC depots are still standing. Agnew is an SP structure, AFAIK. Nothing is left over the hill, except the tunnels, parts of a trestle or two and the Big Trees line. There may be a depot in Felton, but I'm not sure.