Lake Tappan

Lake Tappan is a reservoir impounded by the Tappan Dam on the Hackensack River, straddling the border between the U.S. states of New Jersey and New York. Within New Jersey, the lake traverses the border separating the municipalities of River Vale and Old Tappan in Bergen County, while extending northward across the New York state line into the town of Orangetown in Rockand County. The reservoir was formed in 1967, flooding areas that included the former CAPROC Field Civil Air Patrol airstrip.

The Lake Tappan reservoir covers 1,255 acres (5.1 km²), the majority of its area within New Jersey, and contains 3.5 billion US gallons (13,000,000 m³) of water, with up to 12 to 13 million US gallons (45,000 to 49,000 m³) released downstream daily into the Oradell Reservoir, which lies entirely within Bergen County in New Jersey. The passage of this water between reservoirs can occur in as rapidly as two to three hours.

On March 11, 2003, New Jersey Governor Jim McGreevey visited the reservoir and proposed protecting it as well as the nearby Woodcliff Lake Reservoir and their tributaries with Category 1 water purity status.