Filed Under: Environmental Issues | New York City | Water | Water

New York City Watershed AreaOne of the world's most precious and most threatened resources is safe and ample drinking water. Nearly every city in the United States depends on their local watershed to provide this resource. Watersheds are land areas that collect precipitation and drain to marshes, streams, rivers, lakes, or into the ground, sometimes reaching groundwater stores or aquifers. The legacies of the twentieth century– urbanization of agricultural and forested lands, suburban population increases, development in wetlands and open space, global warming and climate change, the proliferation of toxic chemicals, and the growth of agribusiness - are placing extreme stress on the quality of our water supplies. Furthermore, the amount of water being appropriated for human use continues to grow, placing added pressures on water supplies. New York City is no exception. Drinking Water Supply New York City's 580 million gallon unfiltered water system is generated from the Lower Hudson Watershed. This watershed of 1972 square miles is comprised of three reservoir systems (Catskill, Delaware and Croton) in eight upstate counties east and west of the Hudson River. It is a unique gravity-fed system that serves nearly half the population of New York State. The system provides approximately 1.3 billion gallons of drinking water to over 8 million residents of New York City and approximately 1 million residents of Westchester, Putnam, Orange and Ulster Counties. About 350,000 people in southeast Queens, formerly supplied by the Jamaica Water Supply Company, receive groundwater or a blend of groundwater and surface water. 90% of New York City’s water comes from the Catskill/Delaware systems and 10% from the reservoirs east of the Hudson River. Construction of these reservoirs, dams and aqueduct systems required the relocation of many upstate towns and their residents. The Croton system, which was the first on line, began delivering water in 1842. Distribution System The New York City water system relies almost entirely on gravity to carry water from the Lower Hudson Watershed to the City, with pumping required for only the most elevated areas of the City. By the time the water reaches the Hillview Reservoir in Yonkers, it is 295 feet above sea level and traveling through the system with sufficient pressure to reach the sixth floor of most buildings through gravity alone (which explains why taller buildings have rooftop water tanks). Water collected via 19 collecting reservoirs and three controlled lakes reaches residents by way of a massive distribution network which includes 346 miles of aqueducts and tunnels and 6,890 miles of distribution mains and pipes – some of which are over 125 years old. The system has three main water tunnels. Tunnels No.1 and No. 2 carry water from the Hillview Reservoir to the trunk mains. Tunnel No. 3, under construction since 1970, will provide the city with a third water transportation route and has already improved water pressure, especially in high-elevation neighborhoods. Tunnel No. 3 will be completed in 2020 with nearly 60 miles of thick, subterranean pipe carrying billions of gallons of water snaking out of the Hillview Reservoir and into The Bronx, Manhattan, Queens and Brooklyn. This will also provide a much-needed backup system, allowing the city to shut down, inspect, clean and do major repairs on the system's two aging predecessors: Tunnel No. 1, built in 1917, and Tunnel No. 2, built in 1937. Also, conceptual planning work for a new Kensico-City Tunnel was completed in October 2003. Once complete this aqueduct will supplement the capacity of the three other aqueducts carrying water in the City. In the 1990’s, the NYC Department of Environmental Protection (DEP) embarked on a program to integrate the City’s surface water supply with the groundwater supplied by the aquifer system in southeastern Brooklyn and Queens. The Jamaica Water Supply Company served these communities. However, in 1996, the City purchased the Jamaica Water Supply Company and took responsibility for the delivery of water to the community. Drinking Water Quality New York City drinking water meets all state and federal drinking water standards and is safe to drink. Many do not know that NYC water has historically been considered among the best water in the world. Like all drinking water supplies, New York City's supply requires treatment and monitoring to protect its quality. To protect supplies, aggressive watershed protection measures will be necessary in an era of sprawl development. Treatment: New York City's drinking water is treated with chlorine to kill bacteria, fluoride to prevent tooth decay, orthophosphate to reduce release of lead from household pipes, and sometimes sodium hydroxide to raise the water's pH (i.e. to lower acidity) and reduce corrosiveness. As required by EPA, all New York City water rate payers receive an annual report from the DEP listing what's in their water. The same report is posted in local newspapers and online at the DEP web site (www.nyc.gov/dep). Monitoring: DEP continuously monitors the water in the upstate reservoirs, feeder streams and distribution system. The program also includes over 1,000 sampling stations throughout the City. DEP also monitors the groundwater wells which serve southeastern Queens. The water is analyzed for a broad spectrum of potential microbial, chemical, and physical pollutants. Test results are on the DEP Web site: www.nyc.gov/dep.