The East Branch Delaware River, approximately 75 miles (120 km) long in the U.S. state of New York, is one of two branches, along with the West Branch, that join to form the Delaware River. It flows through a mountainous area on the southwestern edge of the Catskill Park. For a long stretch it serves as the Blue Line, the park's boundary. Much of it is paralleled by state highway NY 30.
The river is a popular destination for fly fishing for brown trout. It was impounded just north of Downsville in the mid-20th century to create Pepacton Reservoir, which supplies drinking water to New York City.
In 1881 John Burroughs, a native of the area, published "A Summer Voyage", recounting a solo boat trip down the East Branch from Arkville to Hancock.