Hey Rudy,
San Gabriel Canyon and the entire San Gabriel Mountains for that matter are filled with herps from Legless lizards and Western Pond turtles to Lyre Snakes and Collared Lizards. There are three people that have focused much of their field research exploring the San Gabriel Mountains, two of which are Michael Long of Eaton Canyon Nature Center and Allen Schoenherr of Fullerton College. The latter of which produced his thesis by studying the San Gabriels and, hence produced a book “The Herpetofauna of the San Gabriel Mountains, Los Angeles County, California” If you do not yet have a copy of this book I suggest obtaining a copy from the Southwest Herpetology Society. The book is filled with Observations and pinpoints canyons and roads where species have been documented. Also, let me know if you ever want to go hiking. Once you get out on your feet and beyond the trash and dirty baby diapers left behind by the average visitor, it is not unusual to come across Western Rattlers, Patch-nosed Snakes, Two-striped Garter Snakes and California Mountain Kingsnakes in plain view streached across paths.

Field Observations of California Amphibians and Reptiles