Not sure exactly for your body of water or for your preferences (wets, dries, streamers or anything) but I will give a few suggestions some of which are already coverd....for nymphs with an indicator....a prince, a pheasant tail or a gold rib hares ear in sizes 14-18 should work also might try a brassie in 18-20 as well. You might also try a globug. If you have a good stonefly population in the river then a stonefly nymph may also catch some fish. All of these I fish with an indicator and usually try to work deeper runs. Actually winter is about the only time I fish nymphs in rivers.
For dries.....a bwo in 18-22, midge patterns 20-24 (personal favorite is a sprout emerger which can imitate either a midge or bwo emerger), and an adams in 16-22. I usually dont use too many dries in the winter unless I see fish rising on a regular basis...where I fish it is usally feeding on midges.
For streamers....buggers, buggers and buggers....I usually fish smaller buggers than a lot of people...I like size 10 or 12 and when the water is colder I tend to cast upstream and then drift the fly downstream, let the fly swing and strip it in slower than normal. (I frequently dont drift it in warmer water and just key on the aggressive fish that will chase it). Most fish in colder water will take it on the drift but you fill find some that hit on the swing or the retrieve. I feel the bugger dead drifted could represent a stonefly nymph so that may be why it works.
These are my opinions and you may or may not find them to be effective for you.
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Take care everyone and cya around. Mark
Take care and cya around,
Mark