Hi G-Man, I welcome another Californian to BigBluegill! A good place for you to try that is not too far from where you live in Garden Grove, is Laguna Lake Park in Fullerton. It can be really good from about now on into the hot months of summer. Also Irvine Lake, but you'll need to take a boat or rent one.
Hey G-Man...you might want to check in with the group 'California Bluegills' on this site under the group listings and they could likely help you with where you can get some good fishing in your area. I am from Maryland...can't help ya much.