Department of Environmental Conservation

D E C banner

Atlantic Ocean/Long Island Sound Watershed

Published Water Quality Monitoring and Assessment Reports

Waterbody Inventory/Priority Waterbodies List Report

Biological Assessment Reports

Other Reports

The Contamination Assessment and Reduction Project (CARP) - A landmark project bringing together federal, state and non-government partners to identify and reduce contamination by PCBs, dioxin and other toxic chemicals within the NY/NJ Harbor Estuary, particularly as it relates to dredged material management.

Watershed Management Plan

All links leave DEC website:

Facts about this Watershed

Map of NYS identifying the Atlantic/Long Island Sound Watershed
Click image to view detailed map of watershed

The Atlantic Ocean/Long Island Sound Watershed drains most of the New York City Metropolitan Area and all of Long Island. Located in the Southeast corner of New York State, the watershed encompasses all marine waters in New York Harbor, Long Island Sound, Block Island Sound, and along the South Shore of Long Island, and the fresh waters that drain into them. The Atlantic Ocean Coastline stretches for 117.5 miles from Rockaway Point at New York Bay to Montauk Point in Eastern Suffolk County.

Location: Southwestern New York State

  • All of Kings (Brooklyn), Queens, Nassau and Suffolk Counties,
  • Much of New York (Manhattan) and Bronx Counties, and
  • Portions of southern Westchester County

Size: 1,650 square miles of land area within New York State.

Rivers and Streams: 522 miles of freshwater rivers and streams. Major tributary watersheds within the larger Atlantic/Long Island Sounds Watershed:

  • Bronx River (63 river/stream miles) 63 river/stream
  • Mamaroneck River (43 miles)
  • Mianus River (43 miles)
  • Peconic River (29 miles)

Lakes, Ponds and Reservoirs: 132 significant freshwater lakes, ponds, and reservoirs (6,728 acres):

  • Kensico Reservoir (2,503 lake/reservoir acres)
  • Lake Ronkonkoma (226 acres)

Estuary Waters: 905,934 acres (1,415 square miles) of marine estuary waters.

Ocean Coastline: 118 miles of Atlantic Ocean Coastline.

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 Atlantic Ocean/Long Island Sound Watershed: