Ramapo River, NJ

The Ramapo River is a tributary of the Pompton River, approximately 30 mi (48 km) long, in southern New York and northern New Jersey in the United States.It rises in a mountainous area of central Orange County, New York, near Monroe and flows southeast to Harriman, then south into western Rockland County, then into northern Bergen County, New Jersey. In New Jersey, it flows SSW, along the east side of the ridge of the Ramapo Mountains. It flows into Potash Lake in Oakland and officially ends at Pompton Lake in Pompton Lakes. The river that flows out of Pompton Lake is still called the Ramapo River until it forms a confluence with the Pequannock River; from then on it is called the Pompton River.

The river is a popular destination for fly fishing of trout. New York State Route 17, the Port Jervis commuter railroad line, and the New York State Thruway were all constructed in the valley of the river between Harriman and Suffern, New York.