Can't speak for California, but I camp/hike a lot in Eastern Washington, also rattlesnake country. A few early encounters unnerved me, all right.
Since then, I've started "belling" myself, the dog, and any others in my party. Theory being that snakes being earless but very sensitive to vibrations, the bell's jangle would warn of our approach in time for them to escape. Sounds dumb, I know...but as proof of its effectiveness I'll offer that I haven't encountered a rattler- or any other wild critters- since I started doing this.
As a side benefit in remote off-leash country, the bell is a constant tracking device on the dog. I can tell exactly where her very-short-self is no matter how tall the brush!