Beaverkill-Willowemoc Fishing Report: September 1, 2026

Quick Summary

The Beaverkill-Willowemoc system has more water than yesterday morning, which helps cover and drift quality, but this is still a measured late-summer trout report. USGS showed the Beaver Kill at Cooks Falls at 382 cfs, 2.34 feet, and 62.1 F during the 8 AM check, while Willowemoc Creek near Livingston Manor was 83.5 cfs, 2.18 feet, and 60.4 F. Those morning temperatures are safe for trout, and recent Catskills source context supports nymphs, wets, small emergers, cripples, spinners, olives, terrestrials, Isonychias, Cahills, caddis, Tricos, and late sulphurs. Fish early or under clouds, carry a thermometer, and treat thunderstorms as the day’s hard stop.

Conditions Snapshot

Field	Value
Status	Fair. Morning water temperatures and added flow are workable, but freestone warming, storms, and selective late-summer trout keep expectations moderate
Flow	382 cfs at Beaver Kill at Cooks Falls; 83.5 cfs on Willowemoc Creek near Livingston Manor
Gauge Height	2.34 feet at Cooks Falls; 2.18 feet at Livingston Manor
Water Temp	62.1 F at Cooks Falls; 60.4 F on Willowemoc Creek near Livingston Manor
Clarity	Not reported by official gauges; inspect each reach after overnight storms before committing to small dries
Trend	Rising compared with yesterday morning on both gauges after rain
Best Window	Morning and cloudy breaks before thunderstorms, then evening only if lightning is gone and water temperatures remain below 68 F
Best Method	Small dries, terrestrials, wet flies, and light nymphs in edges, riffle margins, pocket water, and shaded runs
Wadeability	Limited. Flows are fishable, but fresh rain can make ledges slick and stronger slots pushier than they look

Weather

For Roscoe, the National Weather Service forecast calls for a high near 77 F, light west wind, patchy fog early, and showers and thunderstorms through the day. The hourly forecast showed rain and thunder chances through the morning and higher storm chances again by midafternoon. Cloud cover can extend the trout window, but lightning, quick stain, and afternoon warming are the checks that matter most.

River Notes

The Beaver Kill and Willowemoc both rose from yesterday morning after overnight rain. That is helpful for late-summer trout because the rivers have more depth and broken-water cover, but it does not remove the warm-water rule. Morning temperatures were in the low 60s; by afternoon, use a thermometer and stop targeting trout if readings approach 68 F.

Official gauges do not report clarity. If the Beaver Kill carries stain from local cells, start with soft hackles, small nymphs, or a brief streamer pass in pocket water and softer edges. If clarity is good, fish from the bank first with ants, beetles, small olives, Isonychias, Cahills, caddis, or Tricos before stepping into the near lane. September 1 is beyond the August 31 Horton Brook thermal-refuge closure date noted in prior reports, but anglers should still check posted New York DEC regulations and avoid stressing fish in any warm refuge water.

Hatch Activity

Official gauges do not report hatches. Recent Catskills source context supports Blue Winged Olives, flying ants and beetles, Isonychias, Light Cahills or Summer Stenos, tan caddis, Tricos, and a few fading sulphurs, with the best freestone work still weighted toward mornings, clouds, and safe evening temperatures.

Hatch	Size	Notes
Blue Winged Olive	18-24	Useful in clouds, shade, riffle edges, and soft pockets
Flying Ant, Beetle, or Small Hopper	10-24	Work banks, grass edges, foam seams, and quiet pockets before wading through them
Isonychia	10-14	Fish dries, wets, or swimming nymphs along riffle margins and pocket seams
Light Cahill or Summer Steno	14-16	Useful as a searching dry and for mixed evening rise forms if temperatures allow
Tan Caddis	16-20	Fish pupa or soft hackles through riffles when no steady rises show
Trico	20-24	Possible in calmer morning slicks; use only where water stays cool and fish are feeding steadily
Sulphur	16-20	Late and sporadic, but still worth carrying for cooler windows

Recommended Flies

Category	Fly	Size	Notes
Dry	BWO Comparadun, CDC Olive, or Parachute Adams	18-24	Cover small olives in shaded seams, riffles, and softer pockets
Dry	Flying Ant, foam ant, beetle, or small hopper	10-24	Fish banks, grass edges, and foam seams with a patient drift
Dry	Isonychia Parachute, Light Cahill, Summer Steno, or Sulphur	10-20	Search broken water and be ready for evening surface work if temperatures are safe
Dry	Trico spinner	20-24	Use for calm morning feeders where the water remains cool
Wet	Soft Hackle Pheasant Tail, Partridge and Orange, or Isonychia Wet	12-18	Swing through pocket seams and riffle tails before or between rises
Nymph	Pheasant Tail, Frenchie, Hare's Ear, caddis pupa, or Isonychia Nymph	12-20	Use modest weight and target edges, plunge pockets, and oxygenated riffles
Streamer	Small Woolly Bugger or sculpin	6-10	Worth a short test if rain stain remains or showers add cover

Tactics

Start close. Fish the bank water, soft inside seams, and pocket margins before stepping into the river. On the Beaver Kill, use the added flow to cover riffle shoulders and cushions behind larger rocks. On the Willowemoc, a terrestrial, small olive, or soft hackle can move fish in pockets without much weight. Keep fights short, wet your hands, take a temperature reading before afternoon trout fishing, and leave the water when thunder is near.

Gauge Links

Gauge	Flow	Temp	Link
BEAVER KILL AT COOKS FALLS NY	382 cfs	62.1 F	USGS 01420500
WILLOWEMOC CREEK NR LIVINGSTON MANOR NY	83.5 cfs	60.4 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, clarity, and safety context.