Maryland ·
Gunpowder River Fly Fishing Report - August 8/23/2025
GUNPOWDER RIVER FLY FISHING REPORT
Big & Little Gunpowder Falls — Baltimore / Harford Counties, MD
Report Date: August 23, 2025 | Next Update: August 30, 2025
Current River Conditions
Surface feeding is the story this week. Sulfur activity is strong and caddis are showing later in the day. Water is clear and flows are in the normal low-summer range — great sight fishing opportunities if you match size and presentation.
Flows & Clarity
Flow Rate: ~33–35 cfs (typical summer flows)
Water Clarity: Clear — excellent sight fishing
Notes: Slightly low but steady for late August
Flow Rate: ~33–35 cfs (typical summer flows)
Water Clarity: Clear — excellent sight fishing
Notes: Slightly low but steady for late August
Water Temperature
Current: ~50–54°F (10–12°C)
Daily Range: Stable mornings, slight warm-up midday
Trend: Comfortable for trout; morning bites will be active
Current: ~50–54°F (10–12°C)
Daily Range: Stable mornings, slight warm-up midday
Trend: Comfortable for trout; morning bites will be active
Weather & Wind
Forecast: Warm afternoons, cooler mornings; possible late-afternoon breezes
Wind: Light to moderate — use larger dry profiles if windy
Forecast: Warm afternoons, cooler mornings; possible late-afternoon breezes
Wind: Light to moderate — use larger dry profiles if windy
Access & Parking
Public access at multiple trailheads and state-park pullouts (Big & Little sections). Respect posted signs, gated entries, and private land boundaries.
Public access at multiple trailheads and state-park pullouts (Big & Little sections). Respect posted signs, gated entries, and private land boundaries.
Hatch Chart & Insect Activity (Aug 23, 2025)
| Insect | Size | Activity Level | Prime Time |
|---|---|---|---|
| Sulfur mayflies | #14–16 (pale yellow) | Heavy ⭐⭐⭐⭐ | Afternoon → dusk (1–7 PM) |
| Caddis (various) | #14–18 (tan/olive) | Moderate ⭐⭐⭐ | Late afternoon → evening |
| Midges & Midgy Projectiles | #18–22 | Light–moderate ⭐⭐ | All day in slow water; best around low-light |
| Blue-winged olives (BWO) | #16–20 | Light ⭐⭐ | Cooler mornings & cloudy periods |
| Terrestrials (hoppers, ants) | Size large / bulky | Occasional ⭐⭐ | Warm afternoons on calm banks |
Recommended Flies (matches from fly sheet)
Below are specific patterns that match the hatches and tactics that are working on the Gunpowder right now. Click each fly to view that pattern.
-
Sulfur / Pale Mayfly Dries — for the afternoon hatch:
- Stealth Link Mercer - PMD (PMD / mayfly parachute style)
- Split Case - PMD (emergers / emerger-imitator)
- Caddis — skittering and evening activity:
- Midges & Small Nymphs — slow seams and tails:
-
Top Nymphs (indicator / euro rigs) — get subsurface where trout key in:
- Pheasant Tail Tungsten
- Tungsten Split Case Nymph - PMD
- Tungsten Pat's Rubber Legs (stonefly-style, good on heavier runs)
- Streamers & Sculpin Imitations — use when fish are roaming or after storms:
- Terrestrials (late summer) — for calm, warm stretches:
-
Good all-around attractors:
- Parachute Adams — works when trout are selective but not completely keyed
Tactics & Tips — How to Fish the Gunpowder Right Now
Match the hatch, then refine presentation. Trout are seeing a lot of surface insects — accurate presentation and correct tippet will pay off.
- Afternoon Sulfur Window: Fish pale yellow dries in size 14–16. Use 6X tippet for dry-dropper or pure dry presentations. Focus on foam seams, inside bends and pocket water where fish rise to drifting adults.
- Nymphing: Early morning and low-light calls for nymph rigs. Try an indicator rig with a tungsten pheasant tail or split-case behind a small midge/nymph dropper. Depth and delicate drifts win more than weight.
- Skittering Caddis: When caddis are active later, skitter a tan CDC caddis along pockets and margin seams; fish often take in the slow pockets near structure.
- Streamers: On overcast days or after sudden rises in flow, swing or strip sculpin/baitfish streamers through deeper runs and plunge pools. Articulated sculpin patterns are excellent for targeting large, structure-holding trout.
- Terrestrials: Big warm afternoons with calm wind — throw thick hopper patterns along banks and into seams where trout cruise looking up.
- Leader & Tippet: 9'–12' leaders for dry fly setups. Carry 3–6 lb fluorocarbon (5X–6X) for selective dries and 4–8 lb for nymphing/streamers depending on drag resistance.
- Presentation: Fish slowly and read the water — Gunpowder trout are often keyed to precise drift and may reject blown or dragged flies. Use mends, pick your drift, and keep the leader straight for a natural presentation.
Recent Reports & Local intel
Local shops and recent stream notes indicate consistent surface feeding on sulfurs with strong afternoon rises. Midges and small mayflies maintain steady subsurface action; guides recommend carrying a range of small mayfly emerger/nymphs and pale dry sizes to cover the sulfur windows.
Access, Regulations & Etiquette
- Many public access points run through state park property — observe posted rules and seasonal gate closures.
- Check Maryland DNR for up-to-date regulations (season, catch limits, special restrictions). Some reaches may be popular — share the water and practice low-impact wading.
- Pack out what you bring in. Keep anglers downstream informed when walking through a pool; stealth and patience produce the best results.
Safety & Quick Checklist
Waders: watch mossy rocks and step carefully. Summer sun + cool water = risk of hypothermia if wet; bring layers and a dry change. Always tell someone your put-in/take-out plan.
- Polarized sunglasses (sight fishing)
- Small assortment of sizes: #14–22 dries/nymphs
- 6X and 5X tippet spools for dries; 3–4X for streamers
- Indicator or euro setup for nymphing deeper seams
