The Delaware 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 ...

. It takes water from the Rondout, Cannonsville, Neversink, and Pepacton reservoirs on the west bank of 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 ...

through the Chelsea Pump Station, then into the West Branch, Kensico, and Hillview reservoirs on the east bank, ending at Hillview 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 ...

. Built between 1939 and 1945, the Delaware Aqueduct carries about half of New York City's water supply of per day. At wide and long, it is the world's longest tunnel.

Reservoirs and watersheds

The Delaware Aqueduct carries water from the ,

watershed Watershed may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, an area of land where surface water converges (North American usage) Music * Watershed Music Festival, an annual country ...

using the Rondout, Cannonsville, Neversink and Pepacton reservoirs with the Delaware and Neversink tunnels. (The latter three reservoirs are within the

Delaware River The Delaware River is a major river in the Mid-Atlantic region of the United States and is the longest free-flowing (undammed) river in the Eastern United States. From the meeting of its branches in Hancock, New York, the river flows for a ...

watershed. The water from the Rondout Reservoir is collected as part of the Delaware system, though the

Rondout Creek Rondout Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed October 3, 2011 tributary of the Hudson River in Ulster and Sullivan counties, New York, United States. It rises on Roc ...

is part of the Hudson River watershed.) Combined, the four reservoirs account for of watershed and of capacity, of which goes to the city — half of daily demand. All this water is fed from the Rondout to West Branch Reservoir in Putnam County (part of the

Croton River watershed ''This page is about the Croton River watershed, a hydrological feature. For the component of the New York City water supply system with a similar name, see'' Croton Watershed The Croton River watershed is the drainage basin of the Croton River ...

, which includes the flow of the upstream

Boyds Corner Reservoir The Boyds Corner Reservoir is a reservoir in the town of Kent in Putnam County, New York. Located about 50 miles (80 kilometers) north of New York City, it is the northernmost reservoir in the Croton River watershed, but is not part of the New ...

), then to the Kensico, and Hillview reservoirs in southern

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 ...

, before continuing on to distribution within New York City.

Leak problems

Leaks were first discovered in the Delaware Aqueduct in 1988, with water losses up to per day. The city took many years to analyze the leak problem and devise a solution. In 2010 it announced a plan for a major repair project.

Repairs

The NYCDEP is building a Rondout-West Branch Bypass Tunnel beneath the Hudson River, which will allow it to bypass the leak. Construction began in November 2013. "The number's going to be $1.5 billion to do the entire program to make the fix," said Paul Rush, Deputy Commissioner of the NYCDEP. "About two-thirds of it, $1 billion, will actually go into constructing a bypass tunnel around the location with the most significant leakage in Roseton, and to do additional concrete grouting in the Wawarsing section." The new bypass tunnel is the largest construction project in NYCDEP's history. Construction of the tunnel, under the Hudson, was completed in 2019. The project involved digging two shafts measuring deep. To complete the repairs, the aqueduct was supposed to shut down temporarily in 2022, but this was postponed. The shutdown was rescheduled for 2024–2025; completion of the project depends on potential drought conditions and associated demand levels for water from the Delaware system. The northern section of the tunnel was shut down in September 2024. At the time, the closure was planned to last eight months.

References

External links

"Giant Tube To Supply Water For Ten Millions"
''Popular Mechanics'', August 1937—detailed article with drawings and maps on proposed Delaware Aqueduct {{Authority control Water infrastructure of New York City Landmarks in New York (state) Aqueducts in New York (state) Transportation buildings and structures in Putnam County, New York Transportation buildings and structures in Ulster County, New York Transportation buildings and structures in Westchester County, New York Interbasin transfer

Reservoirs and watersheds

Leak problems

Repairs

See also

References

Further reading

External links