The mountain is named after the West Kill stream which flows along its northern side, and is part of the Devil's Path range of the Catskill Mountains.

West Kill Mountain stands within the watershed of the Hudson River, which drains into New York Bay.

The southeast slopes of the mountain drain into Hollow Tree Brook, thence into Stony Clove Creek, Esopus Creek, and the Hudson River.

The southwest slopes of West Kill Mountain drain into the Broadstreet Hollow stream, thence into Esopus Creek.

This article about a location in Greene County, New York is a stub.