I don't know what the venomous snake are in California, although I know there are rattlers here.
I do know the ones in Kentucky: rattlesnake, copperhead, and water moccasin, at least that's what I was taught as a kid.
While I'm not one who is really afraid of snakes, just the thought of a water moccasin has always freaked me out.
It was never enough to stop me from goin' in the creek, but the one time I thought I saw a snake slither into the water, I shrieked, ran from the creek, and didn't stop until I was back at the house and inside.
That's also the place where I learned why snapping turtles were called snapping turtles.