A 1950s proposal to construct a dam near Tocks Island across the Delaware River was met with considerable controversy and protest. Tocks Island is located in the Delaware River a short distance north from the Delaware Water Gap. In order to control damaging flooding and provide clean water to supply New York City and Philadelphia, the U.S. Army Corps of Engineers proposed building a dam. When completed, the Tocks Island Dam would have created a 37-mile (60-km) long lake between Pennsylvania and New Jersey, with depths of up to 140 feet. This lake and the land surrounding were to be organized as the Tocks Island National Recreation Area. Although the dam was never built, 72,000 acres (291 km²) of land were acquired by condemnation and eminent domain. This incited environmental protesters and embittered local residents displaced by the project's preparations when their property was condemned. After the Tocks Island Dam project was withdrawn, the lands acquired were transferred to the oversight of the National Park Service which reorganized them to establish the Delaware Water Gap National Recreation Area.

The Delaware River is a major river in the Mid-Atlantic region of the United States and is the longest free-flowing (undammed) river in the Eastern United States. From the meeting of its branches in Hancock, New York, the river flows for 282 miles (454 km) along the borders of New York, Pennsylvania, New Jersey, and Delaware, before emptying into Delaware Bay.