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New York City Water Supply

New York City Watershed Program

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. This includes eight million residents of the City and one million consumers located in Ulster, Orange, Putnam, and Westchester counties.

Map of NYC's water supply system

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In order to safeguard this irreplaceable natural resource, a comprehensive and innovative watershed protection plan was developed. It 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.

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 million each day to operate and maintain the filtration plant.

The NYC watershed is located in Southeastern New York State. Most of the water is provided by precipitation (rain and snow) that falls within the watershed, flows to nearby streams, then is collected within the reservoirs. All of the 19 reservoirs and their major tributaries within the NYC Watershed Program are monitored continuously. DEC has published reports available on some of the waterbodies. For more information about the NYC Watershed, see the NYC Watershed page.

Water Quality In the NYC Watershed

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.

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.
  • Excess nutrients, particularly phosphorus. High phosphorus can cause algae blooms that cause serious odor, taste, and color issues. Excess phosphorus can cause nutrient-rich water conditions that support unwanted plant life and increase 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.

DEC's Role

DEC is an active partner in the management and protection of the New York City Watershed Program (NYCWP). Within DEC is the Office of the NYCWP. Formed in 1997, it has staff in Central Office and DEC Regions 3 and 4 who work exclusively on the NYCWP. They offer:

  • Technical expertise and support of watershed protection programs and overall coordination with other federal, New York State, local governments, City of New York, and environmental organizations involved in the NYC Watershed;
  • Direct regulatory and non-regulatory oversight of numerous programs included in the MOA and 2007 Filtration Avoidance Determination within the NYC Watershed. These programs includes:
    • Stormwater Management
    • Wastewater Treatment Plant Upgrades and Construction
    • Community Wastewater Management
    • Septic System Repairs and Replacement
    • Forestry
    • Non-point Source Pollution Control and Management
    • Land Acquisition
    • Stream and Wetland Disturbance Activities

Protecting the Watershed

Each of us lives in a watershed. The Watershed Stewardship page offers tips on actions that people can take to help protect and care for the watershed.

Recreational Opportunities in the NYC Watershed

Ashokan Reservoir

Ashokan Reservoir

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 a short drive of the New York City. The NYC Department of Environmental Protection (DEP) website lists a number of sites and activities available on NYC Watershed protected lands. Although DEP's primary management goal is watershed protection, a significant portion of City-owned lands is open to the public for a variety of recreational uses and other opportunities (leaves DEC website).

On-going New York City Watershed Initiatives

  • East of Hudson Municipal Separate Storm Sewer System (MS4) initiative
  • Total Maximum Daily Load (TMDL) Implementation Plan
  • Pharmaceutical Monitoring and collections from health care facilities

Water Quality Monitoring and Assessment Reports