Delaware Water Gap National Recreation Area - Watersheds

Delaware Water Gap National Recreation Area by National Parks Service

The 330-mile Delaware River and Bay is the centerpiece of a 12,765-square-mile watershed located in the states of Delaware, New Jersey, New York, and Pennsylvania. As major river systems go, the Delaware River Basin is a particularly small watershed - about 0.4 % of the U.S. land area. Sixty U.S. river basins are larger, most are quite a bit larger. Astoundingly, in spite of its small size, the Delaware River Basin provides almost 10 percent of the U.S. population with water (a service area of 20 million people) and the basin has a population greater than 40 of the 50 states (about 8 million people). The largest U.S. city, New York City and the fifth largest U.S. city, Philadelphia, obtain water from the Delaware.

The watershed includes the streams, wetlands, lakes, ponds, and groundwater aquifers that flow to the river, its estuary and the Atlantic Ocean. Other water may not reach the ocean, but re-enters the water cycle through processes such as evaporation, precipitation, and uptake by plants.

The headwaters of the Delaware arise in the Catskill Mountains of New York State. North of Hancock NY, the East ranch and the West Branch meet to form the Delaware River. These two branches of the Delaware supply the New York City metropolitan area with drinking water and with water recreation. Dams on the branches regulate mandated minimum flow in the mainstem. In addition to the two branches, the Delaware has major tributaries in the Neversink, which empties into the river at Port Jervis NY, and the Lehigh, which joins the river at Easton, PA.