You can get there by train from New York City. Trains depart from Penn Station, named "Empire Service", "Maple Leaf" and "Adirondack", stopping at Croton–Harmon station.
Suggested departure point from Crotonville is approximately 2 km from the station (follow signs for Crotonville Campus) heading south-east, on the other side of the Croton River.
(S/E) From the Crotonville campus, take the dirt forest road at the intersection of Hillcrest Avenue and Reservoir Road heading north.
(1) Follow the path straight ahead into the forest heading north. There are no signs, but it is easy to follow the dirt path, which occasionally crosses small paved roads.
(2) Continue north-northeast through the forest until you reach the bridge and dam of New Croton Reservoir.
(3) Take the same route back to the car park where you started (S/E).