Smallbow, many who fish there will tell you you need specific flies & sizes, and some will tell you to go very small. I found that many flies & sizes can work well there. Only once did I ever find that matching the hatch very close was needed on the Gunpowder. I was fishing during a hatch & had nothing in my fly boxes of the size & color, so caught no trout that day. I got plenty of refusals on the few dry flies I had, no interest subsurface & they were only interested in dry flies it seemed. It happens. I did catch a few SM bass & some Bluegills (or other Sunfish species) so for me that day was still a success. There are many who fish midges there in the colder months, and for me streamers, nymphs & wet flies worked well. I rarely fished anything smaller than a size 16. The last trout I caught there was a small Brown, on a Clouser Minnow style pattern that I had tied for Crappies & other panfish.
When I got up into that area, and had time I still made a point of going into those shops to look around & chat even when I didn't really need anything. I always took away some good stream information, and usually, I bought something!
When I was a young man back in the late 70's I fished the Gunpowder often enough, but more so the lower sections near US RT 1, down stream to US RT 40. There were plenty of bass in there & trout too. That was before the sections of river that are now excellent trout waters, became such. It's a unique river for MD, and without travelling to the western reaches of the state, certainly the best trout waters.
I also fished frequently enough, some sections of the Patuxent, Deer Creek and a few lesser known streams, and they all held some trout, plus SM & LM bass & panfish. Deer Creek was a favorite since it was close to the Susquehanna River. I liked to fish the sections of Deer Creek up in Rocks State Park for trout, and the lower end near it's confluence with the Susquehanna for bass. Also fished there for Shad in the spring, but the Shad runs are not what they used to be when I was younger.
Growing up, I wanted to be a fly angler who targeted trout, and I got to fish many of the known trout waters but frankly MD offers much more in the way of warmwater & tidalwater species that were much easier for me to gain access, that most of my fly fishing life in MD was not spent on trout streams. If you ever want any advice for places to target bass or Stripers, give be a holler!
