I've caught some Brown Bull head at night in the Tualatin, they don't get very big at all, 3-4lbs tops. Go with your trout gear if you try, you may lluck into a larger 2-4 pounder. Channell cats are a little more elusive here then people like to think and admit. When I lived in California they were abundant in all running waters.
I caught the Brown Bull heads on worms, liver, and some catfish dough (blood).