www.hdlrc.com
This club is the most active one I belong to (GREAT members, fantastic breeders, and such a fun club to be involved in!), and attracts members (who are also breeders) from AZ, NM, NV, CA, OR, and several other states, and there is now even a labrador breeder from Korea who is a member after attending last year's big specialty show.
If you look at the right-hand side (menu) of the home page, there is a link to a puppy referral coordinator, who has lists of litters (current and expected) that breeders have told her about, and all health clearances (hips, elbows, and eyes at *least*) have been verified for both parents of the litter.
I would probably start there... but that is just me.
For what it's worth, I'm just a bit north of Los Angeles and know a number of members in the above club (obviously), LRCSC (listed in Labby's post- I'm also a member of that one), SDLRC, and Papago.
I don't think you can go wrong with the majority of breeders I know personally from those clubs.
