The Round Valley Reservoir is located in Hunterdon County, New Jersey and became operational in 1965. The 55 billion gallon water storage reservoir was formed by construction of two dams and a dike closing off gaps in a natural horseshoe shaped valley.

The Round Valley Reservoir is an integral part of a water supply system that also consists of Spruce Run Reservoir and the Delaware & Raritan Canal Transmission Complex which together have the capability of delivering 225 million gallons of raw water per day to the water utilities that serve central New Jersey.