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New York City Water Supply

The New York City watershed covers an area of over 1,900 square miles in the Catskill Mountains and the Hudson River Valley. The watershed is divided into two reservoir systems: the Catskill/Delaware watershed located West of the Hudson River and the Croton watershed, located East of the Hudson River. Together, the reservoir systems deliver approximately 1.4 billion gallons of water each day to nearly 9 million people in New York City, much of Westchester County, and areas of Orange, Putnam, and Ulster Counties. 

The Catskill Water Supply System, completed in 1927, and the Delaware Water Supply System, completed in 1967 combine to provide about 90 percent of New York's water supply. The combined Catskill/Delaware (Cat/Del) watersheds cover 1,600 square miles. Water from the Catskill and Delaware systems is mixed in the Kensico reservoir before it is discharged into the Hillview reservoir and on to the distribution system. Drinking water from the Cat/Del System is of high quality and is currently delivered to New York consumers unfiltered (in compliance with the Surface Water Treatment Rule).

The Croton Water Supply System began service in 1842 and was completed prior to World War I. Consisting of ten reservoirs and three controlled lakes, the Croton system has the capacity to hold 95 billion gallons of water and normally provides 10 percent of New York's daily water supply. The Croton Watershed covers approximately 375 square miles East of the Hudson River in Westchester, Putnam, and Dutchess Counties and a small section of Connecticut.


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