Iam not sure, but I heard the San Gabriel river that runs near SLO has a winter run of steelhead. It is not a big run, but its possible to catch fish up to 10lbs. The river has special regulations which are barbless hooks only, and you can only fish on the season opener, wednesdays, weekends, and on major holidays. Wierd regulations, but I think DFG is trying to sustain what is still left of a steelhead run by not letting it get fished out. Im not sure if you can keep any fish or not, but its always more rewarding to release a wild steelhead back to its home.
-just my .02 cents