Most local LEO's are there for crowd control, traffic enforcement and area containment, IF they are even involved at all. From what I have read and understand (only limited so I could be off) the fed's are not even notifying locals in some cases until last minute. Technically, LEO's are to enforce state laws and because of that, most Northern CA city/counties along with LA county in So CA don't co-operate with Fed in a traditional sense. But most of Orange, San Diego, Riverside and San Bernardino Counties have been much more opposed to MMJ and have been more willing to participate with Fed's in local raids and were even part of a law suit that was challenging 215 (unsuccessful so far but is in appeals, most counties have backed out but SD is leading the charge to appeal).
Most counties have either put moratoriums or placed bans on permits for new clubs, this is a city or counties way to stop MMJ in there community without violating state law, they just ban them through zoning laws and regulations. Similar to how some southern states have 'dry counties or cities'.
But some counties (mostly northern and LA) LEO have refused to co-operate with feds in the past and a while back even went so far as to give owners heads up as to raids.