They are open year round. Check the general regs section. This is directly off page 30.
"The following rules and seasons apply unless listed otherwise in the Special Rules. For all game fish and salmon, the Special Rules show ALL of the fishing opportunities for each freshwater area listed."
"LAKES, PONDS, AND RESERVOIRS are open to fishing for game fish (except Dolly Varden /Bull Trout and GRASS CARP) year-round."