A watershed is a geographic area whose rainfall and snow, streams and rivers, all flow or drain into a specific body of water, like a reservoir, river, lake or bay. Ultimately, most watersheds in the U.S. drain into the Atlantic or Pacific Oceans or the Gulf of Mexico. Whether your drinking water comes from a surface supply –– reservoirs, rivers or lakes –– or underground sources called aquifers, everyone lives in a watershed. Water quality protection is important for all of us.

As water travels over the land or through the ground, it picks up naturally-occurring minerals, like arsenic and sodium, as well as contaminants from animals and from human activities.

Pollution sources are classified as point or nonpoint. A point source originates from a single location –– a point. A good example is wastewater treatment plant effluent –– the cleaned water that’s the end product of the process –– which is discharged from a pipe into a river or a stream. Nonpoint sources are diffuse. They don’t have a single point of origin, and are generally carried off the land surface during rain events.

Watershed protection efforts generally focus on the man-made and animal contaminant sources, and are tailored to the type of source (point or nonpoint) and the way the pollutants are moved, like stormwater runoff.

Watershed management is the process of organizing and guiding land and natural resources' use to reflect the competing needs and priorities of all stakeholders. In the New York City’s water supply watersheds, these stakeholders include the water supply’s 9 million consumers, watershed residents and the flora and fauna of the area’s ecological community. With careful planning and communication, water quality can be protected and improved while still serving multiple priorities.

Many scientific studies show the direct connection between the activities within a drainage basin and the diminished quality of its water resources. This happens where there are no management practices and contaminants are simply washed off the landscape by rain or melting snow, or released directly into streams, that then flow into the water supply. The essence of watershed management is to remove or prevent contaminants from reaching the natural flow-path of water.

New York City’s Department of Environmental Protection has a comprehensive watershed protection program which focuses on both protective and corrective initiatives, to ensure that its Catskill/Delaware reservoir system, the source of 90% of the supply’s daily demand, remains unfiltered and sustains its extraordinary high quality.

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