Located in Putnam County in the Towns of Kent and Carmel, approximately 35 miles from New York City, West Branch Reservoir is formed by the damming of the West Branch of the Croton River, which continues south to the Croton Falls Reservoir. It consists of two basins, separated by Route 301 and holds 8 billion gallons at full capacity. It was placed into service in 1895 as part of the City’s Croton Water Supply System.
Today, however, West Branch Reservoir functions primarily as part of the Delaware Water Supply System, serving as a supplementary settling basin for the water which arrives from Rondout Reservoir, west of the Hudson River, via the Delaware Aqueduct. West Branch Reservoir also receives water from its own small watershed and Boyds Corner Reservoir. In addition, West Branch Reservoir is connected to adjacent Lake Gleneida, one of the three controlled lakes that are part of the City’s water supply. Another function of West Branch Reservoir is to receive water pumped in from the Hudson River during drought periods. This water enters West Branch Reservoir from the City’s Chelsea Pumping Station in Dutchess County, 65 miles up the Hudson from New York City. West Branch Reservoir was used very briefly for this purpose during May of 1989 and during the 1965-66 and 1985 droughts. Water withdrawn from West Branch Reservoir ordinarily flows via the Delaware Aqueduct into Kensico Reservoir in Westchester County for further settling. There it mixes with Catskill system water before entering aqueducts that carry it to Hillview Reservoir in Yonkers, at the City’s northern boundary, where it enters the water supply distribution system.
The West Branch watershed’s drainage basin is 20 square miles, and includes portions of the Towns of Kent and Carmel.