Delaware River Project Begins Summary

  • Last updated on November 10, 2022

New York City, facing water-supply demands of more than one billion gallons per day, expanded its supply system by constructing the water system known as the Delaware River Project.

Summary of Event

The Delaware River Project, including the Delaware Aqueduct, quickly became an important component of the water-supply system for New York City, one of the largest cities in the world. This system continues to help the city meet its massive demand for water by using its supply capacity of more than one billion gallons per day. From its inception, the Delaware River Project promised to be an engineering marvel, and it remains the longest continuous tunnel in the world. Since the Delaware River Project is part of a larger water system that developed over the past two hundred years, a study of its evolution is valuable. [kw]Delaware River Project Begins (Mar., 1937) [kw]River Project Begins, Delaware (Mar., 1937) Water;access Delaware River Project Engineering;aqueducts New York City;water system [g]United States;Mar., 1937: Delaware River Project Begins[09410] [c]Environmental issues;Mar., 1937: Delaware River Project Begins[09410] [c]Natural resources;Mar., 1937: Delaware River Project Begins[09410] [c]Government and politics;Mar., 1937: Delaware River Project Begins[09410] [c]Engineering;Mar., 1937: Delaware River Project Begins[09410] Jervis, John B. La Guardia, Fiorello Henry Lehman, Herbert Spear, Walter E.

Prior to 1800, inhabitants of New York City had no public water-supply system. Water was drawn from public or private wells. (One famous well, the Tea Water Pump, provided water that was especially pure and fit for making tea. Some merchants, known as tea-water men, sold the water from carts they wheeled through the city’s streets.) In 1799, a private company began work on the first public water system, which consisted of twenty-five miles of wooden water mains made from logs that had been bored hollow. This system delivered 700,000 gallons of water daily to about two thousand homes. In 1829, a new system was built. It used an elevated cast-iron tank to hold 230,000 gallons of water. This system pumped 21,000 gallons of water per day through twelve-inch-diameter cast-iron water mains.

In 1834, the New York state legislature authorized construction of the Croton Aqueduct project, which began in 1837. The initial cost was estimated at $5.4 million, but by 1842, when the project was completed, its cost had risen to $13 million. The Croton Aqueduct supplied 90 million gallons of water per day to a city population of 360,000. The Murray Hill Reservoir was constructed at Forty-second Street and Fifth Avenue, the modern-day site of the main branch of the New York Public Library. By 1885, New York City’s population was approaching two million, and new demands were being placed on the city’s water system. The New Croton Aqueduct project began in 1885 and was completed in 1893. It was capable of supplying 340 million gallons of water per day to the city. This aqueduct included a thirty-mile tunnel, which was the longest tunnel in the world at that time.

In 1905, the New Croton (Cornell) Dam was completed, which expanded Croton Lake to a length of nineteen miles. This dam was 300 feet high and contained 35 billion gallons of water.

The Catskill water-supply system was initiated in 1907 and was completed in 1927. This system transported water from Esopus Creek and the Ashokan Reservoir, eighty miles northwest of New York City, to the Kensico Reservoir near White Plains, New York. The Catskill Aqueduct Catskill Aqueduct is fourteen feet in diameter and is constructed of seventeen-inch-thick concrete walls. It passes eleven hundred feet below the Hudson River between Newburgh and West Point.

From the Kensico Reservoir, the aqueduct continues fifteen miles south to the Hill View Reservoir near Yonkers. Two distribution tunnels emanate from Hill View Reservoir. Tunnel number 1, completed in 1907, distributes water to Manhattan, while tunnel number 2, completed in 1937, carries water through the Bronx, Queens, and Brooklyn. The two distribution tunnels eventually meet in Western Brooklyn and continue on to supply Staten Island. These tunnels, lined with concrete, were bored through solid rock, at some locations as far as 750 feet below the ground.

By 1933, New York City realized that even more water was needed for the future. Since watersheds northwest of New York City had already been included in the Catskill Aqueduct, the Delaware River basin, farther west, was identified as the next water source. The new system became known as the Delaware River Project and would consist of four reservoirs and miles of new tunnels to be constructed in three stages. A lawsuit by the state of New Jersey, in which the U.S. Supreme Court limited New York to 440 million gallons per day from the Delaware River basin, held up the project for more than two years. Construction of stage 1 began in March, 1937, with an estimated cost of $272 million over twelve years. Stage 1 included construction of the Neversink and Rondout Reservoirs. The Delaware Aqueduct, Delaware Aqueduct which extends forty-five miles, connects these reservoirs with the Croton Watershed. Additional tunnels extend twenty-seven miles to connect with the Kensico Reservoir, then thirteen miles to the Hill View Reservoir. Water then enters one of the two city distribution tunnels and is carried into New York City. The total tunnel length of this aqueduct system is 105 miles.

The aqueduct has a circularly shaped cross section that ranges from 13.5 feet to 19.5 feet in diameter. It is situated between 300 and 2,500 feet below the ground surface. Machinery used to bore the tunnels was lowered down vertical shafts that were up to 19 feet in diameter and up to 1,500 feet deep. Tunnel excavation progressed at the rate of 135 to 270 feet per week, and workers toiled around the clock. Although the project was not interrupted during World War II, available material and human resources were limited and the project was guarded against possible enemy attack or sabotage. The first water from the Delaware Aqueduct reached New York in 1944; stage 1 was completed in 1954 and provided 889 million gallons per day. Stage 2 of the Delaware River Project included a 25.5-mile extension, the East Delaware tunnel, which connected the Rondout Reservoir with the Pepacton Reservoir on the east branch of the Delaware River. Stage 2 was completed in 1955 and carried 375 million gallons per day. The East Delaware tunnel has a diameter of 11.25 feet. Finally, Stage 3 of the Delaware River Project was completed in 1966. Stage 3 included the 39-mile-long West Delaware tunnel, which connected Cannonsville Reservoir on the west branch of the Delaware River with the Rondout Reservoir. The West Delaware tunnel varies in diameter from 11.3 feet to 13.3 feet and has a capacity of 310 million gallons per day.

The Delaware River Project water system was expected to satisfy water requirements for New York City through the year 2000, but given declining overall water usage and per-capita usage, it seems that the water system might well serve the city’s needs indefinitely. In 1970, in order to satisfy New York’s water demand of 1.5 billion gallons per day, digging began on water tunnel number 3 to add 55 miles of tunnel to the existing system; this project was planned to be completed in 2020. Usage generally and steadily declined from the highs of the 1970’s, however, to less than 1.1 million gallons per day in 2003. Per-capita consumption also dropped from a high of 208 gallons in 1988 to a low of 136.6 gallons in 2003.

The demand for water by the people of New York City has grown with the city’s increasing population and burgeoning manufacturing and commercial activities. Development of New York City’s water-supply system has been characterized by its success not only in meeting the demand for quantity but also in delivering high-quality soft water. This availability of ample high-quality water has had a positive economic impact and has contributed to desirable living and working conditions, which attract residents and businesses. The Delaware River Project was completed over a period of time during which water demand increased from 870 million gallons per day in 1927 at the completion of the Catskill Aqueduct to 1 billion gallons per day in 1930, to 1.2 billion gallons per day in 1948. The Delaware River portion of the entire system provides 920 million gallons per day, or one-half of the entire water-system capacity of 1.82 billion gallons per day. This total capacity, given the decline in demand since the 1980’s, seems largely adequate to the area’s needs for the foreseeable future.


Construction of the Delaware River Project had an immediate impact on the environment and on the people of New York in several areas. The most important immediate impact was the provision of sufficient quantity and quality of water to one of the world’s largest metropolitan populations. Other effects included the displacement of people and their homes from land needed for reservoirs, the economic stimulation of the area through job creation and material purchases, and side effects from construction, including noise, dust, and earth displacement.

Each construction phase of the New York City water-supply system included the building of dams to create reservoirs. For the Delaware River Project, damming of rivers created the Rondout, Neversink, Pepacton, and Cannonsville reservoirs. When a reservoir is created, water covers previously dry land. In some cases, entire valleys are filled with water. Land purchased for the Delaware River Project included woods, tillable farmland, and small villages, from which residents were displaced to accommodate the reservoirs. The Rondout Reservoir occupies 3,513 acres and displaced three small villages and 329 people. The Neversink Reservoir covers an area of 93 square miles.

Another immediate impact of aqueduct construction was the creation of jobs. Construction of the Rondout Reservoir, for example, employed 329 people, and the number of employees at the New York Board of Water Supply increased substantially, from 219 to 720, when the Delaware River Project began. The estimated project cost of $272 million was an enormous amount of money, especially in the 1930’s, to add to the economy. Interstate and intrastate competition for water use from the Delaware River Project in the New York City metropolitan area led to the establishment of the State Commission on the Water Supply Needs of Southeastern New York in 1969. This commission was charged with laying the foundation for meeting Southeastern New York’s water needs through the twentieth century, including determining long-range needs, evaluating water resources, analyzing alternative methods for financing, and constructing necessary facilities. The commission also reported on a range of issues affecting future water supply.

Environmental impact on fish and wildlife was cited as a problem resulting from water released from New York City reservoirs. Extreme variations in the quantity, temperature, and time of water release inhibited fish populations and adversely affected recreational opportunities. There was also discussion of a water withdrawal plant on the Hudson River near Hyde Park, New York, to utilize river water, and expansion of the Hinckley Reservoir by ten thousand acres to provide an additional five hundred million gallons of water per day.

The commission contemplated several water-supply technology options. Its considerations included large-scale desalting operations to utilize salt water from the ocean, weather modification using chemicals spread by airplane to seed clouds, and direct and indirect wastewater recycling and reuse, in which wastewater would be treated and injected back into the water-supply system either directly (direct reuse) or at a point in the initial stage of the supply cycle (indirect use) in a process similar to the feeding of a reservoir by a tributary. The commission examined methods of reducing water consumption, such as leakage control of water-main breaks; incentives to use water-saving appliances such as special toilets, showerheads, and washing machines; and innovative water pricing that could penalize any user’s excessive consumption demands.

The Delaware River Project helped to provide water to people in the suburbs of New York City on a long-term basis. Many other municipal water systems were able to obtain water from the New York City system. The New York City water system also allowed conservation of important groundwater resources beneath Long Island, providing water for millions of people, in addition to the people served by the New York City system. Access to and development of watershed areas surrounding the reservoirs was strictly limited to protect water purity; hence natural habitats for wildlife were simultaneously created and protected. Finally, the system yielded exceptionally good water, especially compared with systems of other large metropolitan areas. Water;access Delaware River Project Engineering;aqueducts New York City;water system

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Chiles, James R. “The Fearless Forty of New York’s Water Tunnel.” Smithsonian 25 (July, 1994): 60-69. A description of tunnel excavators working on the expansion of New York City’s water system, which is due for completion in 2020. Provides a brief history and good maps of New York City’s system. Describes the equipment, working conditions, danger, and excitement of excavating tunnel number 3. A very readable article.
  • citation-type="booksimple"

    xlink:type="simple">Conway, E. Virgil. Water for Tomorrow: Recommendations of the Temporary State Commission on the Water Supply Needs of Southeastern New York. Albany: New York State Government Printing, 1973. A report on water use circa 1973, thirty years after the completion of the Delaware Aqueduct. Presents the strategies for water use and production methods dictated by technology during 1973. Good maps of the New York City water system are provided.
  • citation-type="booksimple"

    xlink:type="simple">Galusha, Diane. Liquid Assets: A History of New York City’s Water System. Harrison, N.Y.: Harbor Hill Books, 2002. An excellent work of regional history and a thorough, detailed examination of water in New York City.
  • citation-type="booksimple"

    xlink:type="simple">Garrison, E. G. “Sanitary and Hydraulic Engineering.” In A History of Engineering and Technology: Artful Methods. Boca Raton, Fla.: CRC Press, 1991. A short but interesting discussion of New York City’s water supply. A good review of other hydraulic-engineering projects.
  • citation-type="booksimple"

    xlink:type="simple">Kirby, R. S., S. Withington, A. B. Darling, and F. G. Kilgour. “Sanitary and Hydraulic Engineering.” In Engineering in History. New York: McGraw-Hill, 1956. Excellent chapter dealing with the history of New York City’s water supply, beginning with the late eighteenth century. Excellent illustrations. Map of the reservoir and aqueduct system.
  • citation-type="booksimple"

    xlink:type="simple">Koeppel, Gerard T. “A Struggle for Water.” Invention and Technology 9 (Winter, 1994): 18-31. Excellent historical account of the New York City water system from its inception through development of the Croton Aqueduct in 1842. Includes several enlightening paintings, photographs, and diagrams of the water system.
  • citation-type="booksimple"

    xlink:type="simple">_______. Water for Gotham: A History. Princeton, N.J.: Princeton University Press, 2001. Sometimes slow-paced but well-researched and extremely detailed account.
  • citation-type="booksimple"

    xlink:type="simple">Weidner, C. H. Water for a City: A History of New York City’s Problem from the Beginning to the Delaware River System. Piscataway, N.J.: Rutgers University Press, 1974. This text provides one of the most complete histories of New York City’s water system and includes many details of the system’s development.

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