The fishing is more difficult with the higher flows, but the fish are still there.  You have to use long leaders and tons of weight, but the fish can still be caught.  There are times when you can use dries on the creek, but you'll have more success fishing subsurface.

You can use dries anytime. But I pretty much use dries in the last hour of the day till dark and only if I see fish rising. No risers no dries.
I can remember fishing a hole with a big eddie on the opposite side mid morning. Bwo's were strong and this one fish kept rising in the eddie. I couldnt get a good enough drift with my nymphs in there. After seeing the fish rise and rise again I finally tied on a dry and whacked that trout.