Flowing cold and clear from Prettyboy Reservoir through steep hemlock gorges to Loch Raven, the Big Gunpowder Falls is Maryland’s premier wild-trout tailwater. The bottom-draw dam keeps water temperatures in the 50s even in midsummer, supporting self-sustaining brown-trout populations that rival many Western rivers. A 7-mile Catch-and-Release, Artificial-Fly-and-Lure Only reach anchors the fishery, but public lands extend for more than 20 miles inside Gunpowder Falls State Park. Easy access from Baltimore, prolific aquatic insects, and year-round open seasons make the river equally inviting to first-time dry-fly anglers and technical nymph junkies.
Anglers break the system into three zones. **Upper Tailwater (Prettyboy Dam to Falls Road)**: classic pocket water with narrow slots, plunge pools, and the highest trout density. **Mid River (Falls Road to Blue Mount/Monkton)**: gentler gradient, fertile weed beds, and long slicks that demand stealth and 6X tippet. **Lower River (Monkton to Loch Raven)**: wider banks, cobble riffles, and mixed trout–smallmouth habitat; flows warm by July but winter streamer fishing can be excellent. Each zone has multiple roadside pull-offs and hiking trails for easy exploration.
Wild brown trout (8–16 inches, with 20-inch trophies) dominate the tailwater, while stocked rainbows provide occasional variety in the lower reaches. Brook trout persist in cold tributaries like Bynum Run. Smallmouth bass, fallfish, and redbreast sunfish appear below Monkton during warm months. Strict gear restrictions and barbless-hook rules in the Catch-and-Release reach protect the wild trout population and maintain exceptional catch-rates despite heavy metropolitan angling pressure.
Winter midges and blue-winged olives sustain surface activity on calm days. March brings Little Black Stoneflies and early caddis, followed by sulphur and Hendrickson hatches that define spring. June–July tricos create technical morning match-the-hatch scenarios, while midday terrestrials—ants, beetles, inchworms, and Japanese beetles—keep trout looking up through August. October caddis and autumn olives finish the dry-fly calendar, and streamer bites pick up as water cools. Target overhanging root knobs, submerged wood, and undercut banks where wild browns ambush drifting nymphs and terrestrials.
A 9-foot 4-weight with a supple weight-forward floating line excels for delicate dry-fly deliveries; carry a 10-foot 3-weight euro rod for nymphing the deep slots at Falls Road. Long 12-ft leaders tapering to 6X or 7X are standard. Productive nymph rigs feature #18-22 pheasant-tail variations, zebra midges, or tan caddis larvae. In summer, fish foam beetles, CDC ants, and size 24 trico spinners on 7X. Low-light hours reward 5-weight rods, 4X tippet, and slim sculpin or muddler streamers swung along woody banks.
Falls Road parking area accesses the famed “Crossover” run and Boulder Pools. Masemore Road offers easy river crossings and meadow pockets perfect for dry-dropper sight-fishing. Monkton Station provides bathrooms, trailhead parking, and classic riffle-run sequences. York Road (Big Falls) caters to anglers chasing larger browns with streamers in deeper pools. Hikers willing to walk the Torrey C. Brown Rail Trail between access points often find lightly pressured water teeming with rising fish.
Gunpowder Falls State Park maintains roadside lots at Falls Road, Masemore, York Road, Monkton, and Blue Mount. All sites require no fee but fill quickly on summer weekends—arrive early. The Torrey C. Brown Rail Trail parallels the river for 20 miles, offering foot access to remote water between parking areas. High flows after thunderstorms can create swift, knee-deep crossings; use caution and carry a wading staff. Cell coverage is reliable, but bank erosion and slick schist ledges warrant felt or studded soles.
Essentials: 3- to 5-weight rods, weight-forward floating line, 12-ft 5X–7X tapered leaders, and fluorocarbon tippet. Fly box: CDC sulphur duns (#16-18), trico spinners (#24), parachute ants (#16-18), beetles (#14), tan caddis (#16), pheasant-tail nymphs (#18-22), olive zebra midges (#20-22), and slim sculpin streamers (#6). Felt or Vibram rubber soles with studs grip slick shale; breathable chest waders are comfortable year-round. Bring a small net with rubber bag for safe wild-fish handling and a thermometer to monitor summer water temps.
Cold tailwater releases mask broader threats: siltation from upstream development, invasive Japanese knotweed, and rising summer water temps during droughts. **Gunpowder Valley Conservancy** leads riparian tree-plantings and trash clean-ups. **Gunpowder RIVERKEEPER®** monitors water quality and advocates for science-based Prettyboy Dam flow management. Anglers can help by reporting illegal dumping, using invasive-free felt soles, packing out trash, and volunteering for riparian plant-days that shade the river and lower summer temperatures.
Prettyboy Dam releases are not posted on a strict schedule; flow can rise 100 cfs in under an hour. Check the USGS gauge at Parkton before wading and stay alert for audible increases. Slick, algae-covered shale ledges and hidden drop-offs require studded footwear and a wading staff. Lyme-carrying ticks are common—apply repellent and perform checks after bushwhacking. Summer thunderstorms can fell trees across narrow gorges; exit immediately if lightning approaches.
**Backwater Angler** (Monkton) sits riverside at York Road, offering up-to-the-minute reports, classes, and shuttle advice. **Great Feathers** (Sparks) specializes in Euro-nymph gear, custom dubbing blends, and fly-tying materials. **District Angling** in Arlington stocks Gunpowder-specific patterns and rents demo rods for day trips from D.C. All three shops welcome beginners, sell Maryland fishing licenses, and can recommend local instructors for one-on-one casting lessons.
The **Gunpowder Valley Chapter #305 of Trout Unlimited** spearheads redd surveys, macro-invertebrate monitoring, and habitat restoration. **Gunpowder Valley Conservancy** focuses on land preservation and forest buffer projects, while **Gunpowder RIVERKEEPER®** provides legal advocacy and water-quality sampling. Supporting these groups through volunteer days, membership dues, or donations directly protects the wild browns and clean water that make the Gunpowder a Mid-Atlantic treasure.
From Prettyboy Dam downstream 7 miles to the downstream side of Bluemount Road, the Big Gunpowder Falls is Catch-and-Release, Artificial Flies & Lures Only, with barbless hooks required. The rest of the river follows Maryland’s Put-and-Take Trout regulations, five-trout daily limit, no tackle restrictions. A non-tidal Maryland fishing license and trout stamp are mandatory for anglers 16 and older. Always consult the current Maryland Fishing & Crabbing Guide for in-season stocking closures, special brook-trout protections, and any emergency rule changes.