
Maryland · tailwater
15 miles
Hatch-chart nymphs, dries, and streamers for this river. Not a crowdsourced catch report.
Open the Big Gunpowder Falls River fly list →4 listed points. Map is Vellum land and Teal water — a desk chart, not a satellite.
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Primary access below the dam. Cold releases year-round. Densest fish concentration in the upper beats.
Mid-river access via Bunker Hill Road. Good mix of riffles and pools. Wild browns dominant.
Lower section access. Broader water here. Both wild and stocked fish.
Lower Gunpowder access via Monkton Station trailhead. Good evening caddis hatches in summer.
Maryland fishing license and trout stamp required. Special catch-and-release section below Prettyboy Dam: artificial lures only. Additional regulated sections with size limits — check Maryland DNR for current boundaries and requirements.
Verify with Verify with the local fish and wildlife agency. Retrieved 2026-08-31. Seasons and gear rules change.
The Big Gunpowder Falls River below Prettyboy Dam in northern Maryland is one of the most densely populated trout fisheries in the eastern United States, with fish counts regularly exceeding 3,000 trout per mile in its most productive sections. This extraordinary density makes it one of the few eastern rivers where an angler can realistically encounter multiple fish on every cast during a good hatch, and where even a modest competence at dry fly fishing translates into consistent catches. The Gunpowder is a tailwater in the truest sense: cold dam releases from Prettyboy maintain temperatures below 65 degrees year-round, enabling trout to survive and thrive through Maryland summers when every surrounding stream has warmed out. The fish mix is brown, rainbow, and native brook trout, with wild fish predominating in the upper regulated sections and stocked fish supplementing throughout. The catch is that the Gunpowder''s trout are among the most selective in the region. Three thousand fish per mile means three thousand fish that have been cast over repeatedly, and the browns in particular develop a level of wariness that rewards precise presentation and accurate pattern selection. Blue-winged Olives, Sulphurs, and midges dominate the hatch calendar, with the evening caddis hatch in June and July producing some of the most exciting surface feeding of the year. The river is entirely within Baltimore County parkland, ensuring permanent public access and a protected buffer that keeps development off the banks.
If something here is thin or wrong, add what you know. It goes to review before it publishes.
Contribute to this riverNo USGS site is linked to Big Gunpowder Falls River. We do not invent a site id or guess a flow.