New York City Reservoirs



Pepacton Reservoir

The Pepacton Reservoir on the East Branch in Delaware County was built between 1947 and 1954. The 2,400-foot-long dam at Downsville impounds the largest of the city’s reservoirs. Eighteen miles long, it covers nine square miles, has a 55-mile shoreline and a capacity of 140 billion gallons.


The Pepacton flooded four communities – Arena, Pepacton, Shavertown and Union Grove – displacing 974 people. The city acquired more than 13,000 acres, including cemeteries from which 2,371 bodies were removed to be re-interred elsewhere.


Cannonsville Reservoir

Faced with growing water demand, the city then proposed another reservoir on the West Branch of the Delaware River, a plan that prompted a Supreme Court battle. The court, in 1954, allowed the city to take additional water from the Delaware River system, and New York City immediately began building the last of its reservoirs, the Cannonsville, in Delaware County.


Constructed from 1955 to 1967, the Cannonsville Reservoir was first placed in service in 1965. The Stilesville Dam impounds 95 billion gallons of water in a reservoir that is 16 miles long. Five more communities were condemned to make way for this reservoir: Beerston, Cannonsville, Rock Rift, Rock Royal and Granton. Another 941 people were forced to move.


Water from the Pepacton and Cannonsville Reservoirs is sent to the Rondout Reservoir by gravity via the 25-mile-long East Delaware Tunnel, the 44-mile West Delaware Tunnel and the Neversink Tunnel, which is six miles long. The combined waters are then sent to the city in the world’s longest continuous underground tunnel, the Delaware Aqueduct, which extends 85 miles from the Rondout Reservoir to Hillview Reservoir in Yonkers. The aqueduct, 1,550 feet below ground at one point, runs 600 feet beneath the Hudson River at Chelsea.


*Special thanks to Catskill Watershed Corporation for providing historical accounts of our reservoirs.