The Catskill Aqueduct is an aqueduct in the

New York City water supply system The New York City water supply system is a combination of Aqueduct (water supply), aqueducts, reservoirs, and tunnels which supplies fresh water to New York City. With three major water systems (New Croton Aqueduct, Croton, Catskill Aqueduct, Ca ...

which brings water from the

Catskill Mountains The Catskill Mountains, also known as the Catskills, are a physiographic province and subrange of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined a ...

to Kensico Dam in

Westchester County, New York Westchester County is a County (United States), county located in the southeastern portion of the U.S. state of New York (state), New York, bordering the Long Island Sound and the Byram River to its east and the Hudson River on its west. The c ...

. There it joins with waters from the Kensico watershed and the Delaware Aqueduct. After mixing and settling, the flow from Kensico continues in the aqueduct to the Hillview Reservoir in

Yonkers Yonkers () is the List of municipalities in New York, third-most populous city in the U.S. state of New York (state), New York and the most-populous City (New York), city in Westchester County, New York, Westchester County. A centrally locate ...

for distribution in the City. The aqueduct is fed by the waters of the Schoharie and Ashokan reservoirs 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. The count ...

History

Construction began in 1907. Numerous test shafts were dug to determine the stability of the area's sub-surface geology to ensure both the impermeability of the completed reservoirs and holding strength of their various levees, tunnels, dikes, and dams, and the integrity of the structures of the aqueduct. The aqueduct proper was completed in 1916 and the entire Catskill Aqueduct system including three dams and 67 shafts was completed in 1924.A history of the NYC water supply system - Merguerian, 2000c
/ref> The total cost of constructing the system, less interest on the bonds to finance it, was $177 million ($ in ).

Specifications

The aqueduct consists of of cut and cover aqueduct, over of grade tunnel, of pressure tunnel, and of steel siphon. The 67 shafts sunk for various purposes on the aqueduct and City Tunnel vary in depth from . 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 in Valhalla, New York. Capacity in the section of the aqueduct south of Kensico Reservoir to the Hillview Reservoir in

Yonkers, New York Yonkers () is the List of municipalities in New York, third-most populous city in the U.S. state of New York (state), New York and the most-populous City (New York), city in Westchester County, New York, Westchester County. A centrally locate ...

is per day. The aqueduct normally operates well below capacity with daily averages around 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 in Olivebridge, New York, located in

, which is fed by its own watershed and flow from the upstream Schoharie Reservoir. The aqueduct traverses in a southeasterly direction, first tunneling beneath the Rondout Valley and Rondout Creek in the town of Marbletown, then beneath the Wallkill River in the town of

Gardiner Gardiner may refer to: Places Settlements ;Canada * Gardiner, Ontario ;United States * Gardiner, Maine * Gardiner, Montana * Gardiner (town), New York ** Gardiner (CDP), New York * Gardiner, Oregon * Gardiner, Washington * West Gardiner, ...

before flowing toward Orange County. At Storm King Mountain it crosses below the

Hudson River The Hudson River, historically the North River, is a river that flows from north to south largely through eastern New York (state), New York state. It originates in the Adirondack Mountains at Henderson Lake (New York), Henderson Lake in the ...

to Breakneck Mountain in Putnam County on the east side of the river.The Hudson River Guidebook By Arthur G. Adams
/ref> The aqueduct then enters

Westchester County Westchester County is a county located in the southeastern portion of the U.S. state of New York, bordering the Long Island Sound and the Byram River to its east and the Hudson River on its west. The county is the seventh most populous cou ...

, and flows to the Kensico Reservoir, where it joins with waters of the Kensico drainage basin and the city's Delaware Aqueduct. It continues from Kensico and terminates at the Hillview Reservoir in

. 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