[4] Beginning northeast of Elk Peak, the river flows generally north parallel to Umpcoos Ridge before turning west and receiving Cougar Creek from the right and then Kelly Creek from the right about 32 miles (51 km) from the mouth.

Turning west near RM 14 (RK 23), the river goes over Henrys Falls, meandering generally south-southwest thereafter.

[7] The river supports a steelhead fishery as well as good coastal cutthroat trout fishing near the headwaters.

A hatchery about 9 miles (14 km) upstream of Allegany releases juvenile steelhead to the lower river, but it is difficult to fish downstream of the hatchery because of limited bank access and the dangers of boating through rapids.

[7] Whitewater enthusiasts sometimes run a stretch of the river, about 6 to 9 miles (10 to 14 km) long, that begins upstream of Henry's Falls.