I assume you are referring to Unloaded Open Carry (UOC)? Unloaded open carry is legal in all counties in CA. Here's the thing,
1. Open Carry is legal in CA (and all counties)
2. Know the rules
No open carry in gov't bldgs
No open carry within 1,000ft of a school (GET A MAP w/ schools)
3. CHECK...CHECK...CHECK the local rules. Cities and counties may have certian rules regarding open carry. For example the city of Oakland prohibits UOC in parks!
4. Do a search for your city and county municple codes in google.