The Jacqueline Kennedy Onassis Reservoir (sometimes abbreviated by locals as JKO) – originally and sometimes still known as the Central Park Reservoir – is a decommissioned reservoir in Central Park in the borough of Manhattan, New York City.
The JKO Reservoir covers 106 acres (43 ha) and holds over 1,000,000,000 US gallons (3,800,000 m3) of water. Though no longer used to distribute New York City's water supply, it provides water for the Pool and the Harlem Meer. It is a popular place of interest; there is a 1.58-mile (2.54 km) jogging track around it and it is also encircled by the park's bridle trail. It is often visited by tourists, especially when its double pink "Yoshino" cherries (Prunus x yedoensis), followed by Prunus serrulata 'Kanzan' cherries, are blooming. The rhododendrons along the "Rhusododendron Mile" were a gift to the city from Mrs Russell Sage, in 1909. It is one of the main ecological sanctuaries in the Park, housing more than 20 species of waterbirds: aside from the familiar Mallards and Canada Geese, there may also be seen Coots, Mergansers, Northern Shovelers, Ruddy Ducks, Buffleheads, Loons, Cormorants, Wood Ducks, American Black Ducks, Gadwall, Grebes, Herons and Egrets, along with various species of gulls, making it a popular venue for birdwatchers.