Delaware Watershed

The Delaware River Basin extends to the Catskill Mountains in New York State and stretches more than 330 miles through four states and 42 counties before draining through the Delaware Estuary to the Atlantic Ocean. Philadelphia’s entire land surface ultimately drains to one of seven watersheds that are tributaries to the Delaware River.

The main stem of the Delaware River is the longest free-flowing (undammed) river in the eastern United States, and it serves a variety of important residential and industrial functions, including fishing, transportation, power cooling, and recreational purposes, but is most important as a source of drinking water.

PWD is focused on the management of water resources within our piece of the watershed. Therefore, most of our planning activities related to the Delaware Direct Watershed, which comprises the area of the City of Philadelphia that directly drains to the Delaware River and generally consists of the Delaware River Waterfront and several city blocks of inland area.

This ultra-urban watershed is in the midst of a planning revolution, as the riverfront is undergoing a transformative renaissance, garnering attention from recreational enthusiasts, neighborhood associations, high-rise developers, and international planners.

Watershed Fast Facts


The entire watershed drains nearly 13,000 square miles, of which Philadelphia’s contribution is very small. Approximately 40 square miles of the City of Philadelphia drain directly to the Delaware River.

Stream Miles

The Delaware River Watershed contains approximately 23,700 linear miles of streams. Again, the City of Philadelphia’s contribution is very small, limited to 21 miles of the Delaware River waterfront.


Estimated at approximately 7.7 million residents, approximately 500,000 live in the City of Philadelphia.

Land Use/Impervious Cover

Land use is estimated to be approximately 55% forest, 15% developed, and 26% agriculture throughout the entire watershed. The area within Philadelphia is very densely developed and estimated to be 72% impervious surface.


The Delaware River watershed encompasses areas of four states, 42 counties and all or parts of 838 municipalities in the Mid-Atlantic region.

Help protect your watershed!

Aquatic wildlife markers are an easy way to remind your neighborhood to keep trash and chemicals out of drains.

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