Hatch calendars by river
Maryland trout hatch calendars.
3 rivers covered. Each calendar runs through the full year of mayfly, caddis, stonefly, midge, and terrestrial activity — with peak windows, fly patterns, and water temperature triggers.
Rivers
Maryland hatch waters.
Baltimore County
Gunpowder Falls
Tailwater · brown_trout / wild
Notable hatches
Midge · Blue Winged Olive · Hendrickson
Baltimore County
Big Gunpowder Falls (freestone upper)
Freestone · brown_trout / rainbow_trout
Notable hatches
Midge · Blue Winged Olive · Quill Gordon
Garrett County
North Branch Potomac River
Tailwater · brown_trout / rainbow_trout
Notable hatches
Midge · Blue Winged Olive · Hendrickson
Live water temp + hatch alerts.
Bield: Fish reads USGS gauges and surfaces hatch alerts as water hits the trigger window.