There are definitely a few streams open in the winter, but many are closed. Be sure to check the regs.
The water is likely to be pretty cold so nymphs may work better than dries. I've seen decent hatches on some of the tailwaters in the winter of course, but it is rarer on the freestones and even when there are bugs coming off, the cold flows and higher water often seems to keep fish down. I'm partial to copper johns and similar nymphs that get down quick. Whatever you fish slow and deep is likely the ticket.