Seems like this topic comes up pretty frequent on this board. Lots of misplaced (?) Coloradan's in lala land for whatever reason, so I thought I'd do a java-fueled write up for you lost souls currently suffocating down there.
I've been longboard surfing around LA for about 10 years now during visits to my in-laws. I've tried, with some success, to find good surf kayaking spots, but the reality is that a board is a much better choice, especially considering the waves and access to be found around there.
That said, I will recommend these spots for Kayak Surfing:
El Portal: park in a metered lot as close to the power plant/refinery as possible. head northwest toward the jetty and LAX. This a wicked, hollow beach break when it's on, and then it will be crowded with LA-county's finest dickweeds and not suitable for a kayaker. But during lulls in swell, june-glooms, slop etc., I've found decent uncrowded waves for kayaking wedging along that jetty. The board surfers are beginners and so they scatter, and hopefully most of them won't have walked down that far. Your view is industrial, the summer water is clear with a hint of stank, jumbo jets blast over every five minutes, and the wave is a punchy beach-break that's deep enough to work out some moves. The board surfers during lulls are mostly beginners and so they scatter, and hopefully most of them won't have walked down that far.
County Line: where Malibu meets Ventura county. crowded, awesome right pointbreak on the n end of the beach. never seen this point not a zoo. the rest of the beach is a punchy beachbreak that is wide open and not really all that crowded
for SoCal. Best bets for not getting boxed out as a kayaker, again, are to choose small, crumbly days when the body boarders are out. This is an hour north of Santa Monica, but the drive is through Malibu so the scenery and wildlife viewing can be specatular.
Zuma: miles of OK, uncrowded beach-break in Malibu that's usually breaking too close to the sand for most boater's comfort. Spend some more time playboating in these tricky waves and you may learn to like it. It's worth a check on the way up to county line, or on the way back if you got skunked or punched out at county line.
Sunset: where sunset boulevard meets the Pacific. a good, mellow right point with several takeoffs. only good for plastic as it's littered with rocks. a zoo with longboarders most always. but they can be dealt with and paddled around--usually. I included Sunset because it's close, and it's also the break to check when conditions are bumpy and big. usually a mixed up storm swell will thin it out and leave the place empty and full of large, off-speed rollers great for butt-bouncing. if the launch from the rocks/staircase is gnarly, paddle out from the sandy, more protected beaches towards Santa Monica. Don't swim, wear earplugs, and swallow as little water as possible.
On a general note, a good bet for kayak surfing in LA county is to go check out all the primo spots when the ocean is confused. Most of the surfers down there are spoiled with clean waves, so many unreal spots have kayaking windows if you're savy and know where to look.
For whitewater options, please visit the California Whitewater Community here: