To the south it is bordered by the combined watershed of the Rondout Creek and Wallkill River. On the northeast is the Kaaterskill Creek basin, with the West Kill draining the Spruceton Valley to the northwest into Schoharie Creek, a long tributary of the Mohawk River, itself the Hudson's longest tributary. On the western boundary, water drains into the East Branch of the Delaware River; the two upper branches of the Neversink, the Delaware's largest left tributary, rise along the Esopus basin's southwest boundary, with the Neversink's East Branch headwaters flowing a thousand feet from the Esopus' source at Winnisook Lake.