Gauge Description:

Season: April and May are generally the best months for the Grass, but Oct and Nov also offer windows of boatable flows following three or four days of good rain.

Flows: The USGS gauge on the Oswegatchie in Harrisville provides an "approximation". The benchmarks below have many variables, so make sure you assess each rapid yourself.

If Harrisville guage is dropping add 150 cfs to the gauge level.

At higher flows be prepared for Copper Rock Falls to be even larger, making portage almost necessary. The wave trains for the other rapids will also become large with bigger holes.

As the water drops, and is below 1000 expect to bump and scrap into rock while running each rapid.

Gauge Information

Name Range Difficulty Updated Level
WEST BRANCH OSWEGATCHIE RIVER NEAR HARRISVILLE NY
usgs-04262500 600 - 3000 cfs II-III(V) 01h47m ~ 284 cfs (too low)
This gauge is not on the Grass, it is a good reference point, but does not actually represent the flow for the Grass river
gauge graph
RangeWater LevelDifficultyComment
600 -3000 cfs barely runnable-high runnable II-III(V) gauge is important or has warning These are a rough estimate and may not actually represent the minimum and maximum flows needed.

Reports give the public a chance to report on river conditions throughout the country as well as log the history of a river.

When River/Gauge Subject Level Reporter
7y30d17h12m @Grass, Upper South Branch Spruce Mountain to New Bridge [NY] Copper Rock Falls 750 cfs Gregory R. Miller
7y30d17h13m @Grass, Upper South Branch Spruce Mountain to New Bridge [NY] Copper Rock Falls 750 cfs Gregory R. Miller
7y30d17h16m @Grass, Upper South Branch Spruce Mountain to New Bridge [NY] Copper Rock Falls 750 cfs Gregory R. Miller