The Esopus Creek watershed is divided into two parts by the Ashokan Dam. The area above the dam is commonly referred to as the Ashokan Basin. Below the dam is the Lower Esopus watershed. The Lower Esopus is generally cut off from the watershed above the dam except for controlled reservoir releases and spillway overflows. 

The entire Esopus Creek watershed area (upper and lower) is 425 square miles.  Flow from the 256 square miles of the upper drainage area has been regulated by the Ashokan Reservoir since 1913 to supply New York City drinking water via the Catskill Aqueduct. About 12.2 miles upstream of the reservoir, additional water enters the creek through the Shandaken Tunnel, which has diverted water from Schoharie Creek since 1924. The flow in the lower Esopus Creek represents the drainage from 169 square miles of watershed combined with spillage or releases from the upstream reservoir. 

The Lower Esopus watershed has two sub-basins (Plattekill Creek and Sawkill Creek). The lower creek is divided into three stream segments based upon distinctive geology, topography, and hydrology, ending in a tidal estuary at its mouth.

Diversions from Plattekill Creek at the Blue Mountain Reservoir provide drinking water for the Village of Saugerties. A slight diversion occurs at the headwaters of the Sawkill into Cooper Lake for water supply of Kingston. Water is also diverted from the Lower Esopus Creek for agricultural irrigation.

The Lower Esopus remains an important water resource that provides environmental and economic value to the communities it traverses and to the landowners along its banks. To learn more about the history and ecology of the watershed, see “A Journey through Lower Esopus Creek” (2011).