The
Kensico Reservoir is a
reservoir located in the towns of Armonk (North Castle), Harrison and Valhalla (Mount Pleasant), New York. It was formed by the old earth and gravel dam, build in 1885, which impounded waters from the
Bronx and
Byram rivers, and supplied about 18 million gallons daily. The construction of a new
masonry dam in 1915, replaced the old dam, and expanded the water supply by bringing water from the
Catskill Mountains over a distance of more than 100 miles. It is about 3 miles (5 km) north of downtown
White Plains, New York, and about 15 miles (24 km) north of
New York City. The reservoir serves mainly to store the waters received from the Catskill Mountains west of the Hudson River. Along with the
West Branch Reservoir and
Boyds Corner Reservoir, it is one of only three reservoirs within the
Catskill/Delaware system outside the
Catskill Mountains region.