It may be cold but there are some large rainbow trout in the North Yuba right now. You’ll have the best luck with a streamer or nymph in the deeper water. If you can get on the water before the snow melts and increases the flows, you’ll find some larger fish that have come into the river from Bullards Bar Reservoir.
Bring layers and be ready for the big temperature swings.
Right now, there is not bait fishing allowed and you can’t keep any of your catch. This river is well patrolled by Game Wardens. You can get your fishing licence online or at the hardware store in Downieville.