Van Cortlandt Lake at Van Cortlandt Golf Course. The lake results from the Van Cortlandt family damming Tibbetts Brook to power some mills. Tibbetts Brook emptied out into the Harlem River, and still does, but now it has been diverted into the sewer system at the foot of the lake. By the way, Mosholu Parkway gets its name from the Algonguian name for Tibbets Brook.

References:

1. Van Cortlandt Park: Tibbetts Brook.
2. Duncan, Steve, The Forgotten Streams of New York.