Lake DeForest is a reservoir in Clarkstown, New York created in 1956 by impounding the Hackensack River that is part of the water supply for Rockland County, New York and Northern New Jersey, notably Bergen and Hudson counties. It was originally developed by the Hackensack Water Company which had been under the direction Robert W. de Forest from 1881 to 1926. It is now owned and operated by United Water and is the most upstream of its three reservoirs along the river, the others being Lake Tappan and the Oradell Reservoir. It has a storage capacity of 5.6 billion gallons. The lake is traversed by a causeway carrying Congers Road (CR 80).