1thoughfish, this is one tough assignment...
Check out this link of
Parks/Lake in Los Angeles.
Alondra Park appears to be the nearest with fishing. Have no clue if it gets stock with trout.
El Dorado Park is your best bet (look it up in the above link)., it's about a 20min drive (depending on traffic). And it does get stocked with trout, during the cooler months. Hint: Try a sliding sinker rig with power bait on a size 18 treble hook ... toss that sucker as far out as you can get it ... let it rest, kick back and enjoy a soda and hope for the best.
Sliding Sinker Rig
The rig is very simple. Take a small egg-shaped sinker and slip it on your main fishing line. Tie the end of the line to a small barrel swivel (without a snap attached), and then tie on 18 to 24-inches of two- to four-pound test leader material to the other end of the swivel. It is best to use leader material is lighter in breaking strength than your regular fishing line. To the end of the leader, tie on a No. 16 or 18 treble hook. Mold a small ball of floating bait around the treble hook, just covering all of the hook points. Use as light a sinker and swivel as possible that will still allow you to cast a good distance from shore with your fishing gear. Using two- to four-pound test line on spinning tackle generally allows for longer casts and the use of 1/16 to 1/8th ounce egg sinkers. If you have six- or eight-pound test line on your reel, you can still use this rig with 1/4-ounce sinkers, but you need to use lighter leader (two- to four-pound test) material to attach to your swivel and hook.
Good luck., let us know how it goes...