Home > Basin Information
Basin Information
The Delaware River
The Delaware River at Trenton, N.J. Photo courtesy of The Watershed Institute.
The Delaware River at Trenton, N.J. Photo courtesy of
The Watershed Institute. 

Before we talk about the Delaware River Basin, let's talk about the Delaware River

•  Longest undammed river east of the Mississippi; tidal and non-tidal

•  330 miles long; an interstate river its entire length; whenever you stand on one bank, you look across at another state

•  Headwaters: East and West Branch Delaware River confluence at Hancock, N.Y.

•  Mouth: Delaware Bay at Cape May, N.J./Lewes, Del. (where it meets the Atlantic Ocean)

•  Tributaries: more than 2,000, incl. 216 major ones; largest are the Schuylkill and Lehigh rivers, respectively - both in Pennsylvania

•  Non-Tidal River: 200 miles from Trenton, N.J. north to its headwaters in N.Y.; clean, high-quality waters

     • Part of DRBC's Special Protection Waters Program

     • 75% in the National Wild & Scenic Rivers System

•  Tidal River: 133 miles from Trenton, N.J. south to the Delaware Bay; aka the Delaware Estuary, where the river's freshwater mixes with the ocean's saltwater

     • The Delaware Estuary is part of the National Estuary Program, which protects estuaries of national significance; managed by the Partnership for the Delaware Estuary

     • While the entire tidal river is part of the estuary, salinity levels vary from the Delaware Bay (saltwater) to Wilmington, Del. (brackish) to Philadelphia, Pa. and Trenton, N.J. (mostly freshwater).

     • The tidal change also varies; in the Delaware Bay, the tidal change is about six feet, but in Trenton, it is about ten feet. 

A Clean Water Success Story

•  The Delaware River has come a long way from its polluted past in the late 1800s to mid 1900s, and its clean-up is hailed as one of the world's top water quality success stories.

     • Historic Dissolved Oxygen Levels & Recovery

     • The Clean Water Act: 50th Anniversary

•  Today, the Delaware River is cleaner; it supports 100s of species of wildlife and people are flocking back to its banks to live, work and play. It is proof that a living and a working river can coexist.

     • Delaware River: American Rivers' 2020 River of the Year

     • Migratory fish - for example, the American shad and the endangered Atlantic sturgeon - and resident fish are supported by the river; the upper Delaware is also a world-class trout fishery.

     • Bald eagles reside or overwinter all along the river, surviving on fish as their primary food source    

     • Horseshoe crabs breed on the shores of the Delaware Bay more than any other place in the world 

     • Recreation & Tourism: Boating/paddling, fishing, birding and both land and water trails. The riverbank is home to numerous marinas, greenways and parks.  

     • Delaware River Port Complex (including docking facilities in Pennsylvania, New Jersey & Delaware): largest freshwater port in the world

         • 2017 Delaware River Port Study: 90 million tons of cargo moved through the regional ports, supporting over 190,000 jobs and over $85 billion in total economic activity (from a Maritime Exchange for the Delaware River and Bay 2018 news release)

         • Port Cargo: Includes petroleum and petrochemical products, container cargo, forest products and automobiles. It is the largest North American port for steel, paper and meat imports, as well as the largest importer of cocoa beans and fruit on the East Coast. Over 65% of Chilean and other South American fruits imported into the United States arrive at terminal facilities in the tri-state port complex. Wilmington, Delaware is home to the largest U.S. banana importing port, handling over one million tons of this cargo annually from Central America.

The Delaware River Basin
Illustration of the Delaware River Basin.

What is a Basin? What is a Watershed?

•  A Basin is a large watershed; it can be made up of smaller sub-watersheds. A watershed is the area of land draining to a particular stream. When it rains, the rain will run-off the land into a waterway; both the waterway and the surrounding land make up the watershed. All of the watersheds that eventually drain to the Delaware River make up the Delaware River Basin.

The Delaware River Basin

•  Includes 10 main sub-watersheds & five physiographic regions (Appalachian Plateau; Ridge and Valley; New England; Piedmont; and Atlantic Coastal Plain)

•  Area: 13,579 square miles, incl. the 782 square-mile Delaware Bay. 

•  Includes four states, 42 counties, and 868 municipalities.

     • Pennsylvania (6,422 square miles or 50.3 percent of the basin's total land area);

     • New Jersey (2,969 square miles, or 23.3%);

     • New York (2,362 square miles, 18.5%); and

     • Delaware (1,004 square miles, 7.9%)

•  Land cover varies from mostly tree canopy in the northern portion of the basin to more urbanized and farmland in the southern section. As expected, more impervious surface occurs in the more developed/urbanized sections of the basin. 

•  Large Size-to-Service Ratio: Drains only four-tenths of one percent of the total continental U.S. land area, but over 13.3 million people (~4% of the U.S. population) rely on its waters for drinking, agricultural and industrial use.

•  Water Use: Nearly 6.4 billion gallons of water are withdrawn from the basin each day; this includes ground and surface water withdrawals for a variety of uses, the main three being thermoelectric power generation, public water supply, and industry.

     • Supports the water needs of two of the nation's largest cities: Philadelphia and New York City, as well as ~one million people in northern New Jersey. 

     • Consumptive Use: Over 850 million gallons a day; this is water withdrawn from the Basin but not returned. The biggest consumptive users are out of basin diversions for NYC and northern N.J., which total almost 2/3 of all water in the basin that is used consumptively.

•  Economic Engine: Supports a water-based economy of over $20 billion dollars annually, from recreation, water quality, water supply, hunting/fishing, ecotourism, forest, agriculture, open space and port benefits; supports ~600,000 jobs.

Related Resources