I spend a couple weeks a summer in the bay area and have never found anyone to paddle with or anything decent with water, except surfing of course. It seems like all the decent looking streambeds I have seen in the area are usually dry and would only run when rainfed (i.e. midwinter), if at all. Admittedly, I do not know squat about paddling in California and have never tried hard enough to find anything in that area as I am always there for other reasons. I'd be interested in any people and beta you discover.
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD