The Lake Tappan reservoir covers 1,255 acres (5.1 km²),[1]:222 the majority of its area being within New Jersey, and it 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.