The Catskill Aqueduct, part of the

New York City water supply system A combination of aqueducts, reservoirs, and tunnels supplies fresh water to New York City. With three major water systems ( Croton, Catskill, and Delaware) stretching up to away from the city, its water supply system is one of the most exte ...

, brings water from the Catskill Mountains to

Yonkers Yonkers () is a city in Westchester County, New York, United States. Developed along the Hudson River, it is the third most populous city in the state of New York (state), New York, after New York City and Buffalo, New York, Buffalo. The popul ...

where it connects to other parts of the system.

History

Construction commenced in 1907. The aqueduct proper was completed in 1916 and the entire Catskill Aqueduct system including three dams and 67 shafts was completed in 1924. The total cost of the aqueduct system was $177 million ().

Specifications

The aqueduct consists of of

cut and cover A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

aqueduct, over of grade tunnel, of pressure tunnel, and nine miles (10 km) of steel siphon. The 67 shafts sunk for various purposes on the aqueduct and City Tunnel vary in depth from 174 to . Water flows by gravity through the aqueduct at a rate of about . The Catskill Aqueduct has an operational capacity of about per day north of the

Kensico Reservoir The Kensico Reservoir is a reservoir spanning the towns of Armonk ( North Castle) and Valhalla ( Mount Pleasant), New York, located 3 miles (5 km) north of White Plains. It was formed by the original earth and gravel Kensico Dam constructed in 18 ...

Valhalla, New York Valhalla is a hamlet and census-designated place (CDP) within the town of Mount Pleasant, in Westchester County, New York, United States, in the New York City metropolitan area. Its population was 3,162 at the 2010 U.S. Census. The name was in ...

. Capacity in the section of the aqueduct south of Kensico Reservoir to the

Hillview Reservoir The Hillview Reservoir is a storage reservoir in southeastern Yonkers, New York. It was built within a six-year period from 1909–1915 by the New York City Board of Water Supply to receive water from the newly constructed Catskill Aqueduct, w ...

Yonkers, New York Yonkers () is a city in Westchester County, New York, United States. Developed along the Hudson River, it is the third most populous city in the state of New York, after New York City and Buffalo. The population of Yonkers was 211,569 as en ...

is per day. The aqueduct normally operates well below capacity with daily averages around 350– of water per day. About 40% of New York City's water supply flows through the Catskill Aqueduct.

Geography

The Catskill Aqueduct begins at the

Ashokan Reservoir The Ashokan Reservoir (; Iroquois for "place of fish") is a reservoir in Ulster County, New York. It is at the eastern end of the Catskill Park, and is one of several in the region created to provide the City of New York with water. It is the ci ...

Olivebridge, New York Olivebridge is a hamlet in the town of Olive, Ulster County, New York, United States, within Catskill Park and the Catskill Mountains. The community's name is sometimes written Olive Bridge, but the United States Board on Geographic Names gives t ...

, located in

Ulster County Ulster County is a county in the U.S. state of New York. It is situated along the Hudson River. As of the 2020 census, the population was 181,851. The county seat is Kingston. The county is named after the Irish province of Ulster. History ...

. From the

, the aqueduct traverses in a southeasterly direction through Ulster, Orange, and Putnam counties. It tunnels first beneath the Rondout Valley and Rondout Creek in the town of Marbletown, then beneath the Wallkill River in the town of Gardiner in Ulster County before flowing toward

Orange County, New York Orange County is a county located in the U.S. state of New York. As of the 2020 census, the population was 401,310. The county seat is Goshen. This county was first created in 1683 and reorganized with its present boundaries in 1798. Orange ...

. It crosses below the Hudson River bed at Storm King Mountain in Orange County before reaching Putnam County on the east side of the river at Breakneck Mountain. The aqueduct transports water from Ashokan as well as the Schoharie Reservoir, which feeds into Ashokan.The Hudson River Guidebook By Arthur G. Adams
/ref> The aqueduct then enters

Westchester County, New York Westchester County is located in the U.S. state of New York. It is the seventh most populous county in the State of New York and the most populous north of New York City. According to the 2020 United States Census, the county had a population ...

, and flows to the

, which also receives water from the City's

Delaware Aqueduct The Delaware Aqueduct is an aqueduct in the New York City water supply system. It takes water from the Rondout, Cannonsville, Neversink, and Pepacton reservoirs on the west bank of the Hudson River through the Chelsea Pump Station, then into ...

. It continues from the Kensico reservoir and terminates at the

. The Hillview Reservoir then feeds City Tunnels 1 and 2, which bring water to New York City. If necessary, water can be made to bypass both reservoirs.

History

Specifications

Geography

References

See also