Department of Environmental Conservation

D E C banner

Delaware River Watershed

Published Water Quality Monitoring and Assessment Reports

Biological Assessment Reports

Groundwater Study Reports and Data

The links below go to United States Geological Survey (USGS) web pages. DEC partners with the USGS to conduct research and publish reports and data for groundwater resources of the state. An overview of the monitoring project for the entire state, including links to methods, maps, and publications, can be found on USGS's 305(b) Ambient Groundwater Quality Monitoring webpage.

Watershed Management Plans

Third Brook Watershed Management Plan (Offsite link)

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:

  • 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):

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

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.

More about Delaware River Watershed: