The Lower Deschutes in the Warm Springs area has been good for Trout and Steelhead. Nymph rigs are definitely your best bet, but I have heard on some days of a BWO hatch coming off and bringing fish to feed on the surface.
The Maupin area is a year round opportunity, but remember that waters adjacent to the Warm Spring Reservation close Dec 31st.
I can remember fishing a GREAT baetis hatch in an eddy near Maupin on Super Bowl Sunday several years ago. So don’t forget what is out there mid winter.