Gunpowder Falls
Prettyboy Tailwater · Baltimore County
Baltimore County, Maryland, USA
Open live forecast →Target species: Brown and Rainbow.
Stream gauge: 01582500. Flow and water temperature update on every refresh.
Weekly AI Outlook as of 06/05/26
At 78 cfs, the Gunpowder is running in prime summer form with cold tailwater temps keeping trout active while area freestones warm. Early June means Green Drake time — watch for the brief but explosive hatch that makes this Baltimore County gem shine. With highs pushing near 90°F, focus morning and evening sessions when sulphurs and caddis are most active. The cold release keeps this fishable all summer while other regional waters heat up.
- Flow: 78 cfs — excellent summer level for wade fishing with good coverage in runs and pocket water
- Hatches: Green Drake window opening, sulphurs peaking evenings, spotted sedge caddis active — CDC Sulphur #16, Elk Hair Caddis #14
- Water Temp: Cold tailwater release keeping temps in ideal 54-62°F range despite air temps approaching 90°F
- Best Window: Early mornings before 9am and evenings after 6pm — avoid midday heat stress on both fish and angler
Generated weekly from live USGS gauge readings, weather forecasts, and recent fly shop reports. Updates Friday mornings.
About this Water
- Tailwater
- Best months: Year-round; peak Apr–June and Sept–Oct
The Gunpowder Falls below Prettyboy Reservoir in northern Maryland is the mid-Atlantic's most productive tailwater trout fishery within easy reach of Baltimore. Cold releases from Prettyboy Dam create year-round trout habitat through Gunpowder Falls State Park. The river holds stocked and increasingly wild brown trout, with rainbow trout in select stretches. The Hereford Zone catch-and-release section produces the most consistent fishing. Hatches mirror the broader mid-Atlantic: Hendrickson, Sulphur, and a strong summer Trico hatch.
The Gunpowder Falls supports wild brown trout reproduction within sight of Baltimore's metropolitan area — a tailwater fishery within commuting distance of one of the East's largest cities.
January Outlook
The Gunpowder Falls below Prettyboy Dam is one of the most accessible year-round tailwater trout streams in the Mid-Atlantic. January midge fishing in the fly-fishing-only section produces wild brown and rainbow trout for Baltimore-area anglers year-round.
Productive Patterns
- Zebra Midge
- RS2
- Scud
- Soft Hackle Midge
Tips
January on the Gunpowder is quiet and productive. The fly-fishing-only section above Masemore Road is the best water. Midge nymphing in the slower pools between the riffles. The Gunpowder State Park setting is beautiful in winter.
Water Notes
Prettyboy Dam release. 50–300 cfs. Water 44–52°F. Year-round tailwater. Cold but consistently fishable.
February Outlook
February tailwater fishing on the Gunpowder. The dam release keeps conditions stable. Early BWO activity on mild afternoons begins building toward the spring season.
Productive Patterns
- Zebra Midge
- BWO Nymph
- RS2
- Soft Hackle Emerger
Tips
February on the Gunpowder produces best on mild afternoons above 45°F. The upper fly-fishing-only section near the dam is the most productive. Clear, slow-moving sections require fine tippet — 6X minimum.
Water Notes
50–200 cfs. Water 44–52°F. Stable tailwater. Early BWO activity on warm afternoons.
March Outlook
March brings the beginning of serious spring fishing on the Gunpowder. Hendrickson hatches start and caddis begin. The fly-fishing-only section is exceptional for wild brown and rainbow trout.
Productive Patterns
- Hendrickson #12-14
- Blue Winged Olive
- Elk Hair Caddis (small)
- Pheasant Tail
Tips
The Gunpowder's Hendrickson hatch is one of the finest in the region — this is where Baltimore-area fly fishers make their annual spring pilgrimage. Fish the slower sections of the fly-fishing-only water. Clear water demands stealthy wading.
Water Notes
50–400 cfs. Water 46–54°F. Spring tailwater conditions. Hendrickson hatch building through the month.
April Outlook
April is the Gunpowder's finest month. Hendrickson, caddis, and Blue Quill hatches produce excellent surface fishing. The fly-fishing-only section holds exceptional wild trout. One of the Mid-Atlantic's premier April rivers.
Productive Patterns
- Hendrickson Dry #12
- Blue Quill #18
- Elk Hair Caddis
- March Brown
Tips
April on the Gunpowder is outstanding — multiple hatches produce consecutive surface activity from 1pm to dark. The fly-fishing-only section from the dam to Monkton is excellent. Position carefully in the productive runs and wait for the hatch.
Water Notes
60–400 cfs. Water 48–56°F. Prime spring tailwater conditions. The Gunpowder's finest month.
May Outlook
Sulphur and caddis season on the Gunpowder. Evening Sulphur hatches from 6-9pm are the highlights. Wild trout in the fly-fishing-only section are in peak condition feeding on abundant hatches.
Productive Patterns
- Sulphur Sparkle Dun #16
- Elk Hair Caddis
- Light Cahill
- Blue Winged Olive
Tips
The evening Sulphur hatch is the Gunpowder's signature experience — position early and fish the consistent rises in the flat sections above Masemore Road. The wild fish are educated but catchable with precise presentations. 5X-6X tippet.
Water Notes
50–300 cfs. Water 52–60°F. Excellent spring conditions. Evening Sulphur hatch from 6-9pm.
June Outlook
Early summer on the Gunpowder. Green Drake hatch arrives in early June. Terrestrial fishing beginning. The tailwater keeps the fly-fishing-only section productive as surrounding freestone streams warm.
Productive Patterns
- Green Drake #10
- Elk Hair Caddis
- Yellow Sally
- Ant
Tips
The Green Drake hatch on the Gunpowder is brief but spectacular — fish rise aggressively to these large mayflies. The tailwater's cold release makes the Gunpowder an excellent summer option as Baltimore's surrounding streams warm.
Water Notes
40–200 cfs. Water 54–62°F. Summer conditions beginning. Fish mornings and evenings.
July Outlook
Summer terrestrial season on the Gunpowder. Ants, beetles, and tricos produce the summer program. The tailwater keeps temperatures manageable. Fish the morning trico spinner fall and evening sessions.
Productive Patterns
- Trico Spinner #22-24 (dawn)
- Flying Ant #18
- Beetle
- Elk Hair Caddis (evening)
Tips
The Gunpowder's Trico spinner fall in July is excellent — be on the water at first light in the flat sections. The tailwater keeps water temperatures below 65°F even in Baltimore's summer. The fly-fishing-only section is the best urban tailwater refuge in the region.
Water Notes
30–150 cfs. Water 56–64°F (tailwater). Air temps 85–92°F. Dawn trico fishing, evening caddis.
August Outlook
August continues summer patterns on the Gunpowder. Trico spinner falls at dawn, terrestrials through the day, and evening caddis carry the fishing through the hottest Maryland summer weeks.
Productive Patterns
- Trico Spinner #22-24
- Ant
- Beetle
- Elk Hair Caddis (evening)
Tips
The Gunpowder's proximity to Baltimore makes it the go-to water for urban area fly fishers in August. Dawn fishing for the trico spinner fall is excellent. The tailwater stays cool enough for active fish through the summer. Fish the slower flat sections.
Water Notes
25–100 cfs. Water 58–66°F. Summer low water. Tailwater character keeps conditions fishable.
September Outlook
Fall returns excellent conditions to the Gunpowder. BWO hatches on overcast afternoons and pre-spawn brown trout aggression create some of the best fishing of the year.
Productive Patterns
- Blue Winged Olive #18-20
- Elk Hair Caddis
- Trico Spinner
- Streamer
Tips
September on the Gunpowder is excellent — the transition from summer heat to fall brings both improved fishing conditions and reliable BWO hatches. Large wild brown trout become aggressive in the fly-fishing-only section. One of the finest September tailwaters in the Mid-Atlantic.
Water Notes
40–250 cfs. Water 54–62°F. Outstanding fall tailwater conditions.
October Outlook
Prime fall fishing on the Gunpowder. Pre-spawn brown trout are aggressive and the fly-fishing-only section holds trophy fish. Mahogany Dun and BWO hatches produce excellent afternoon dry fly fishing.
Productive Patterns
- Mahogany Dun #14-16
- Blue Winged Olive
- Streamer
- Copper John
Tips
October on the Gunpowder is exceptional — large pre-spawn browns move into the best lies and feed aggressively. Streamer fishing at dawn for trophy fish, then switching to dry flies for the afternoon hatch. The park setting is beautiful in fall.
Water Notes
50–300 cfs. Water 48–56°F. Outstanding fall conditions. Prime month for trophy brown trout on the Gunpowder.
November Outlook
November late season on the Gunpowder. Post-spawn brown trout feed aggressively. Late BWO activity on mild afternoons. The year-round special reg section keeps fishing available into winter.
Productive Patterns
- Blue Winged Olive
- Midge Nymph
- Soft Hackle
- Streamer
Tips
November on the Gunpowder is excellent and less crowded than fall peak. Post-spawn fish are aggressive and BWO hatches continue on mild days. The proximity to Baltimore means the river is accessible year-round but November brings near-solitude.
Water Notes
50–350 cfs. Cooling 42–52°F. Late season tailwater conditions. Post-spawn trout feeding aggressively.
December Outlook
December returns the Gunpowder to winter mode. The year-round fly-fishing-only section remains open. Midge fishing for Baltimore-area anglers seeking winter trout in a beautiful state park setting.
Productive Patterns
- Zebra Midge
- RS2
- Scud
- Soft Hackle Midge
Tips
The Gunpowder in December is the Mid-Atlantic's finest urban winter tailwater. The dam release keeps water flowing year-round and the state park is quiet. A short drive from Baltimore for winter midge fishing — an underrated local gem.
Water Notes
40–200 cfs. Water 42–50°F. Year-round tailwater. Cold but fishable. A unique Baltimore-area winter resource.
Hatch Calendar
| Insect | Peak | Active | Size | Productive Patterns |
|---|---|---|---|---|
| Blue-Winged Olive Baetis tricaudatus |
Apr, Oct | Mar, Apr, May, Sep, Oct, Nov | #16–20 |
|
| Sulphur Ephemerella dorothea |
May, Jun | May, Jun, Jul | #14–18 |
|
| Midge Chironomidae spp. |
Jan, Feb, Mar, Dec | Jan, Feb, Mar, Apr, Oct, Nov, Dec | #20–26 |
|
| Caddis (Spotted Sedge) Hydropsyche spp. |
Jun, Jul | May, Jun, Jul, Aug, Sep | #14–16 |
|
Access & Approach
Hereford, MD is the primary base. Gunpowder Falls State Park provides extensive public access. Maryland fishing license required. Catch-and-release / artificial only in designated stretches.
Nearby Fly Shops
- Backwater Angler
- Fish Talk Magazine
Regulations & License
Fishing in Maryland requires a current license. Always verify season dates, bag limits, and any special-regulation waters before you fish.
Maryland fishing regulations & license →
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About Current
Gunpowder Falls conditions on Current combine real-time flow data (USGS, WSC, CDEC, CEHQ), weather, tide predictions, hatch probabilities calibrated to this specific water, and recent fly shop reports from the area.
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