Bouquet Reservoir is the one in Saugus that was mentioned. There isn't any camping there, and there isn't even any public access to the reservoir. As was already stated, most of the lakes in the southern California area are high use, and generally only have developed campgrounds. There are some areas in central California that you may wish to consider, such as the Fresno County Lakes area (Shaver Lake is the most well known). Some campsites near Courtright Reservoir are only accessible by 4WD or boat. There are some other smaller lakes that are 4WD access only (Coyote Lake for example). There are numerous lakes in the area, and some require 4WD to access them, but most of the larger ones fall into the high use category, like most of the lakes in southern California.
The suggestion for the Mammoth area is good, as is most of the rest of the eastern Sierra. The June Lake loop, while high use and fairly developed, is beautiful and worth seeing. Further north, you may wish to check out the Lee Vining area, Virginia Lakes, or the lakes around Bridgeport. Most of these are also fairly developed and high use, but there may be a few lesser traveled areas to explore.