Beaverkill-Willowemoc Fishing Report: August 18, 2026

Quick Summary

The Beaverkill and Willowemoc are usable this morning, but this is still a careful summer freestone report. USGS showed the Beaver Kill at Cooks Falls at 471 cfs, 2.59 feet, and 65.1 F, while the Willowemoc near Livingston Manor was 106 cfs, 2.29 feet, and 62.8 F during the 8 AM check. Those temperatures are below the 68 F trout-stress line at report time, but the Beaverkill is close enough that anglers should carry a thermometer and keep the day short if the water warms. Local Catskills context points to humid weather, flying ants, strengthening Blue Winged Olives, tapering sulphurs, and good nymph or wet-fly work in riffles before any surface window develops.

Conditions Snapshot

Field	Value
Status	Fair. Morning temperatures are fishable, but the Beaverkill is close enough to 68 F that trout ethics and afternoon warming matter
Flow	471 cfs at Beaver Kill at Cooks Falls; 106 cfs at Willowemoc Creek near Livingston Manor
Gauge Height	2.59 feet at Cooks Falls; 2.29 feet near Livingston Manor
Water Temp	65.1 F at Cooks Falls; 62.8 F near Livingston Manor during the 8 AM check
Clarity	Not reported by official gauges; check color at the access after recent rain
Trend	Falling from yesterday's higher rain-influenced readings
Best Window	Morning through early afternoon while temperatures stay safely below 68 F
Best Method	Nymphs and wet flies in riffles and pocket water; dry flies if olives, ants, or evening mayflies bring fish up in safe temperatures
Wadeability	Limited on the Beaverkill and better but still cautious on the Willowemoc; avoid fast pushy crossings

Weather

For Roscoe, the National Weather Service forecast calls for morning fog giving way to mostly sunny skies, a high near 78 F, and light northwest wind around 5 mph. Tonight is forecast partly cloudy with areas of fog and a low around 54 F. The cooler morning is the useful trout window; brightening skies and a high near the upper 70s mean the thermometer should decide how long to keep fishing.

River Notes

Both Catskills freestone gauges dropped from yesterday morning's rain-influenced readings: Cooks Falls moved from 561 cfs to 471 cfs, and the Willowemoc moved from 142 cfs to 106 cfs. That improves footing compared with the higher water, but it does not remove the summer-temperature issue. The Beaverkill was already 65.1 F during the morning check, so the safe trout window may be shorter there than on the colder Willowemoc reaches.

A same-day Catskills local report described a rainy, humid start and warned about changing conditions, including heavy thunderstorm potential and flood-watch context from the wet pattern. The National Weather Service point forecast for Roscoe had a calmer, mostly sunny day at the 8 AM check, so treat this as mixed-source uncertainty: official point weather looks manageable now, but recent rain still makes color, footing, and temperature worth checking at each access. The Beaverkill Horton Brook thermal refuge regulation remains in effect from the Iron Bridge at Horton downstream to the first Route 17 overpass, where angling is prohibited from July 1 through August 31.

Hatch Activity

Official gauges do not report hatches. Same-day Catskills source context supports flying ants in the humidity, Blue Winged Olives gaining importance as August progresses, sulphurs tapering, Hebes and White Flies becoming more important, and Isonychias and Light Cahills in faster water toward evening. Fish the hatch only while water temperature remains safe.

Hatch	Size	Notes
Blue Winged Olive	18-22	Increasingly important in late August, especially with clouds or softer light
Flying Ant	16-20	Humid conditions make ants worth carrying for banks, flats, and foam seams
Sulphur	16-18	Tapering, but still part of the late-summer mix where water stays cold enough
Hebe	18-20	Carry small pale mayflies for mixed Catskills surface activity
White Fly	12-14	Evening option where temperatures remain safe
Isonychia	12-14	Nymphs and wet flies are useful in riffles and faster bankside water
Light Cahill	14-16	Possible in broken current and lower-light evening water

Recommended Flies

Category	Fly	Size	Notes
Nymph	Isonychia Nymph	10-14	Start in riffles, pocket water, and faster edges with good oxygen
Nymph	Pheasant Tail, Frenchie, or Hare's Ear	14-18	Match sulphur and small mayfly nymphs before surface feeding starts
Nymph	Caddis Pupa	14-18	Work riffles and pocket water when fish stay subsurface
Wet	Soft Hackle Pheasant Tail, Partridge and Orange, or Isonychia Wet	12-18	Swing through broken water during active bug movement
Dry	BWO Comparadun or CDC Olive	18-22	Use for small riseforms under clouds, shade, or evening light
Dry	Flying Ant or Beetle	16-20	Prospect shaded banks and foam seams during humid spells
Dry	Sulphur Emerger, Hebe, White Fly, Isonychia, or Light Cahill	12-20	Carry a broad late-summer dry mix, but fish it only while temperatures remain safe

Tactics

Take a thermometer reading before choosing a beat. If the Beaverkill is already near 68 F, move to colder water or stop targeting trout rather than trying to force a hatch. If temperatures are safe and the water has enough clarity, nymph or swing wets through riffles, pocket water, and faster seams where fish have oxygen and cover. Switch to olives, ants, or a dry-and-emerger pair only when fish are actually showing. Avoid the Horton Brook thermal refuge closure and do not wade hard crossings that are still pushy from the recent rain.

Gauge Links

Gauge	Flow	Temp	Link
BEAVER KILL AT COOKS FALLS NY	471 cfs	65.1 F	USGS 01420500
WILLOWEMOC CREEK NR LIVINGSTON MANOR NY	106 cfs	62.8 F	USGS 01419500

Sources

Official sources checked: USGS stations 01420500 and 01419500, plus the National Weather Service forecast for the Roscoe, NY area. This report is an original Custom FlyBox summary based on current official gauge and weather data, with local public conditions reports reviewed separately for hatch, method, closure, and safety context.