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Facts About The NYC Watershed

Why is the NYC Watershed unique?

The New York City drinking water supply system is the largest unfiltered water supply in the United States (US). It provides approximately 1.2 billion gallons of high quality drinking water to nearly one-half the population of New York State every day.

Consumers include:

  • Eight million NY City residents
  • One million residents in Westchester, Putnam, Orange, and Ulster Counties.

In order to safeguard this irreplaceable natural resource a comprehensive and innovative watershed protection plan was developed and is embodied in the historic and landmark New York City Watershed Agreement (MOA). The MOA was signed in January 1997 and is a partnership agreement.

Partnership Members include:

  • New York City agencies
  • The upstate communities
  • The U.S. Environmental Protection Agency and other federal agencies
  • The New York State Department of Environmental Conservation (DEC) and other state agencies
  • Members of the environmental community

The partnership was organized to protect and to ensure that New Yorkers continue to enjoy high quality, affordable drinking water and to avoid the need for costly filtration - a cost estimated at between $8.0 to $10.0 billion to construct the facility and approximately $1.0 million each day to operate and maintain the filtration plant.

Where does the NYC water come from?

The NYC watershed is located in Southeastern New York State. The watershed consists of 3 separate political watersheds overlapping parts of geographical watersheds:

  • Croton Watershed (map): located east of the Hudson River in Putnam, Dutchess, and Westchester counties and provides about 10% of the daily consumption and up to 30% during drought situations.
  • Catskill and Delaware Watersheds (map): located in Delaware, Greene, Schoharie, Sullivan, Ulster, and portions of Putnam and Westchester counties east of the Hudson River, provides about 90% of daily consumption.
  • Contains a network of 19 reservoirs within a 2000-square-mile watershed that extends 125 miles north and west of New York City.

Most of the water is provided by precipitation (rain & snow) that falls within the Watershed and is collected within the reservoirs. All 19 of the reservoirs and their major tributaries within the NYC Watershed Program are monitored continuously. Water is then transferred to the City of New York through a series of tunnels and aqueducts. Prior to entering the distribution system the water is disinfected with chlorine. Once treated, water is then sent directly to consumer's taps for use.

For additional information on the New York City Watershed, visit the Lower Hudson Estuary Watershed page, the Lower Hudson River Watershed Reports page, and the NYC Watershed Reservoirs page.

How is the water?

Water from the NYC Watershed is considered to be the "Champagne" of drinking water. It consistently wins annual taste tests against other NYS water sources. The majority of the water (i.e., Catskill and Delaware Watersheds portion) is of very high quality and continues to meet all federal and state drinking water quality standards without the need for filtration.

Water Quality Issues within the NYC Watershed

Some significant water quality concerns in the NYC Watershed are:

  • Sediment problems, or turbidity, within the Catskill Watershed. Sediment can transport pathogens and interfere with effectiveness of water filtration and disinfection. More about turbidity water quality issues in the NYC Watershed (link).
  • Excess nutrients, particularly phosphorus. High phosphorus can cause algae blooms that cause serious odor, taste and color issues. Excess phosphorus can cause eutrophic water conditions and increased carbon. This water, then mixed with chlorine, can result in the formation of "disinfection byproducts" - chemicals that are suspected of being carcinogenic and may cause the risk of early term miscarriages.

What You Can Do!

Each of us lives in a watershed. On our Watershed Stewardship page are some tips on actions that you and your friends can take to help protect and care for your watershed.

Recreational Opportunities on the NYC Watershed Lands

The NYC Watershed contains some of the greatest recreational and sporting opportunities in New York State. Enjoy the natural environment, delve into history, and enjoy numerous sporting activities, all within minutes of the busy city. For more information, visit New York City's Watershed Recreation webpage (leaving NYSDEC's webpages).

Important On-going Initiatives within the New York City Watershed

Summary of Safe Drinking Water Act Projects
Summary of Water Resources Development Act Projects

Published Water Quality Monitoring and Assessment Reports

NYC DEP Drinking Water Supply and Quality Report
Croton Pesticide Monitoring Report
Waterbody Inventory/Priority Waterbodies List
Bioassessment Reports - Esopus Creek

More about Facts About The NYC Watershed:

  • NYC Watershed Reservoirs - A listing and additional information on the 19 reservoirs located within the NYC Watershed protected lands.