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Delaware River Watershed

A brief overview of this watershed and its water quality is presented below. For more detailed information about the Delaware River Watershed, published NYSDEC reports are also available. General information about watersheds is available at the "We All Live in a Watershed" webpage.

Facts about this Watershed

Map of NYS identifying the Delaware River Watershed
Click to view a detailed map of this watershed

The Delaware River Watershed (12,800 square miles) covers parts of New York, Pennsylvania, New Jersey and Delaware. About one-fifth of the upper watershed lies within New York State. These headwaters originate in the Catskill Mountains and eventually flow into Delaware Bay and the Atlantic Ocean. The Delaware River (and a portion of the West Branch) serve as the border between New York and Pennsylvania.

Location: Southeastern New York State

  • Most of Sullivan and Delaware Counties,
  • Portions of western Orange and Ulster and eastern Broome Counties, and
  • Small parts of Greene, Schoharie and Chenango Counties.

Size: 2,390 square miles of land area within New York State

Rivers and Streams: 4,062 miles of freshwater rivers and streams. Major tributary watersheds to the 79 miles of the Delaware River in New York State include:

  • East Branch Delaware River (1,285 river/stream miles)
  • West Branch Delaware River (981 miles)
  • Neversink River (626 miles)
  • Mongaup River (344 miles)

Lakes, Ponds and Reservoirs: 188 significant freshwater lakes, ponds, and reservoirs (24,932 acres), including:

  • Pepacton Reservoir (5,185 lake/reservoir acres)
  • Cannonsville Reservoir (4,605 acres)
  • Neversink Reservoir (1,469 acres)

How is the Water?

Water Quality in The Delaware River Watershed

In the Delaware Watershed, about 53% of river/stream miles, and 61% of lake, pond and reservoir acres have been assessed (see Assessment Report).

Water quality Pie Chart. Rivers: 53% good, 21% Satisfactory, 2% Poor, 24% unassessed. Lakes: 0% good, 1% satisfactory, 54% poor, 45% unassessed
Good water quality: Fully supports designated activities and uses
Satisfactory: Fully supports designated activities, but with minor impacts
Poor (Impaired): does not support designated activities and uses
Unassessed: Insufficient data available

Water quality in the Delaware River Watershed is very good in many respects. Most of the water quality concerns in the watershed are associated with the protection of the quality of the waters of the New York City water supply reservoirs rather than current impacts or impairments in the watershed. Currently there are only five waterbodies in the watershed that are considered to have impaired uses. These impairments are largely the result of atmospheric deposition of pollutants - mercury and acid rain - from outside the watershed.

Major water quality concerns in the watershed are:

  • Acid Rain which limits the fish community and aquatic life
  • Atmospheric Deposition of Mercury which restricts fish consumption
  • Protection of New York City Water Supply Reservoir (Pepacton, Cannonsville, Neversink)

About Water Quality in New York State

Water chemistry sampling in a NYS stream
Water Chemistry Sampling

Each waterbody in NYS has been assigned a classification, which reflects the designated "best uses" of the waterbody. These best uses typically include the ability to support fish and aquatic wildlife, recreational uses (fishing, boating) and, for some waters, public bathing, drinking water use or shellfishing. Water quality is considered to be good if the waters support their best uses. NYSDEC routinely monitors and assesses water quality throughout the state and publishes detailed reports of these findings. For more information on these monitoring and assessment programs, see Water Quality Monitoring, Assessment and Planning.

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 your watershed.

Biological kick sampling in a NYS stream
Biological Kick Sampling

Published Water Quality Monitoring and Assessment Reports

Watershed Management Plans

More about Delaware River Watershed: