New Jersey

Delaware River Basin

The Delaware River touches four states and affects millions of people.

The Delaware River begins its 400-plus-mile journey in New York’s Catskill Mountains, where cool springs establish the river’s East and West branches. Further south, the branches meet in Hancock, New York to form one of the only free-flowing major rivers remaining in the eastern United States.

With more than 300 miles designated “wild and scenic,” the Delaware is a river of tremendous biological, economic and cultural significance. Nearly 20 million people along the East Coast rely on its water for drinking and industrial purposes. They share the resource with shad, sturgeon, eel and other species that migrate through the river. Anglers and kayakers enjoy the Delaware’s scenic beauty, protected in places by five national park properties.

Mammals including bobcat, beaver, bear and fox roam throughout this watershed that also contains an important segment of the Atlantic flyway. Each year, more than 200 species of birds spend part of their life cycle here.

The shores of the Delaware River Estuary, in Delaware and New Jersey, provide critical spawning grounds for horseshoe crabs and hosts one of the most critical stopover points for migrating shorebirds in the western hemisphere.


Although it remains undammed, the Delaware faces a variety of serious and growing threats, as human demands for water outstrip nature’s ability to provide. Among the many stresses are nutrient runoff and sedimentation from agricultural, industrial and residential sources, and invasive species—which threaten the existence of many native species and natural communities. Further down the river, climate change poses another threat; rising sea levels are creating serious concern that the Delaware’s “salt line” may move up the river, threatening Philadelphia’s water supply.

But one of the most challenging threats lies in the way the river flows. Approximately 50 percent of the Delaware's headwaters is diverted to New York City’s municipal water supply system, and never returns to the watershed. The withdrawals and releases that accomplish this diversion cause profound changes in the natural flow of the river—the periodic changes of water level, volume, scouring and flooding that create the specific habitats upon which the river’s life depends. These flow alterations are threatening the survival of freshwater animals like mussels, crayfish and amphibians—among the species most at risk in the United States—and the health of the entire river system.

Land use changes along the river’s edges also cause dramatic changes in the way the water moves. The river’s floodplains are rich stores of biodiversity, and serve as critical natural regulators of the water coursing down the river. Their thickly accumulated soils and dense floodplain forests slow the course of seasonal floods and help absorb the impact of storm events. But the Delaware’s floodplains have seen heavy development, and fewer are left to gentle the river’s rush. Recent years have seen unprecedented destruction from repeated heavy floods in the middle and lower stretches of the river.

The Big Picture

Using grant money from the National Fish and Wildlife Foundation, the Conservancy and its partners are developing a set of shared restoration goals and strategies that address multiple threats in the four-state watershed. 

In November 2011, the Delaware River Basin Conservation Initiative – a collaborative effort between The Nature Conservancy, Partnership for the Delaware Estuary, and Natural Lands Trust – completed a conservation blueprint that will help ensure a healthy Delaware River and Bay.

This coordinated effort prioritizes the protection actions needed to restore ecosystem function and biodiversity across the basin. Not only will these integration efforts help to make the landscape ecologically healthy and more resilient—especially to broader issues like climate change and overfishing—it will also make the most of limited human and financial services.

Taking Action — Everyone's River

While the Conservancy is assessing big-picture conservation needs within the basin, it at the same time continues its current on-the-ground efforts in each of the Delaware River Basin’s four states. Here’s a snapshot of current work taking place at the state level:

Delaware – The Conservancy in Delaware has for many years worked to safeguard places throughout the Delaware Bayshores. Protections efforts include:

New Jersey – The Conservancy in New Jersey is actively protecting land and water within the Delaware River basin. Protection efforts include:

  • High-quality tributaries of the Delaware River in the Kittatinny Ridge and Valley Priority Conservation Area.
  • High-quality streams at the Minisink Valley and Little Flatbrook Preserves.
  • Critical migratory bird habitat throughout Delaware Bayshores at places like Gandy’s Beach, Sunray Beach and Hand’s Landing Preserves.
  • Floodplains and uplands at Manumuskin River and Maurice River Bluffs Preserves. 

New York – The Conservancy in New York is protecting the Delaware Basin using a variety of methods.  Protections efforts include:  

  • A three-year status assessment of abundance and distribution of the American eel. Results will help inform future conservation and fisheries management plans. 
  • Dam removal. The first dam removal for ecological reasons took place in 2004 when the 185-year-old Cuddebackville dam, located on the Neversink River, was removed. This opened up 40 miles of the Neversink River for the first time in almost 100 years.
  • Development of a state-of-the-art system of water management. The system accommodates the natural range of variability in river flow, which is critically important for sustaining aquatic life while at the same time balancing human needs for water.

Pennsylvania – The Conservancy in Pennsylvania is studying how the Delaware River functions, and taking action to allow it to flow as naturally as possible. Protection efforts include:

  • An extensive study on the Delaware’s natural seasonal flow. This information will inform decisions about water withdrawals and reservoir releases.
  • Identification of undeveloped land that could serve natural floodplain functions.



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