On the north side Rusk Mountain and the peaks to its west form the boundary between the West Kill watershed and the Schoharie's. South of the range from Southwest Hunter Mountain to Mount Sherrill drainage flows into Esopus Creek, another Hudson tributary in Ulster County. The unnamed peaks over in elevation between Halcott and Vly mountains on the southwestern boundary are part of the Catskill Divide, since the Vly Creek basin on the opposite side is part of the Delaware River watershed. On the northwest is the smaller watershed of the Little West Kill, another Schoharie tributary.