Conditions

Sources

River list based on “Fly Fishing the Catskills”, a NY State DEC guide by Ed Van Put, formerly of the DEC Bureau of Fisheries.

Streamflow, gauge height, and water temperature from the USGS Water Services API (instantaneous, daily, and statistics services). Data is provisional and subject to revision.

Weather forecasts and rain chances from the National Weather Service API, read at each river’s own forecast gridpoint. A rain chance of 70%+ in the next 24 hours caps a river’s rating at “Fair.”

Water clarity is an estimate, not a reading. Only one of the gauges we follow reports turbidity, and its sensor is offline more often than not — so clarity is inferred from how fast a river’s flow is changing. Sediment rides the rising limb of a flood and settles out as it drops, so the same river runs dirtier going up than coming down (USGS on turbidity hysteresis). We check the live flow against yesterday’s average: up 35% reads as off-color, doubled reads as blown out, and high water that has stopped rising reads as clearing. Those cut-offs were calibrated against a year of paired flow and turbidity readings on the Esopus at Coldbrook, the one gauge that measures both, taking 10 NTU as the line between clear and not. USGS is explicit that estimating sediment from flow alone is less accurate than measuring turbidity directly, so treat this as a hint to check the water yourself, not a substitute for looking at it.

One exception, and it’s deliberate: the West Branch Delaware and the East Branch Delaware get no clarity warning at all. Both are gauged close below a water-supply reservoir, where a jump in flow is usually a scheduled release of settled, clean water rather than runoff — the same test run on a below-reservoir gauge was wrong about three times in four. Rather than cry mud every time a dam opens, we stay quiet on those two.

On those same two we now read the gauge below the dam itself, so a rise the release accounts for is called clear rather than passed over in silence — with the dam named, so you can check it. The West Branch’s gauge sits about three and a half hours below Cannonsville, and a change only counts once it has had time to get there.

The Neversink is below a reservoir too, but we gauge it at Bridgeville rather than at the dam, far enough down that most of the water is tributary inflow and a rise usually does mean rain. So it gets the ordinary clarity treatment. We still show what Neversink Reservoir has done, without saying when a change reaches Bridgeville — we have not been able to measure that.