About Round Valley Recreation Area
Round Valley Reservoir, covering 2,350 acres and reaching depths of approximately 180 feet, is the largest reservoir and second-deepest lake in New Jersey, holding up to 55 billion gallons of water at full capacity. Formed in 1960 by the New Jersey Water Authority through the damming of the South Branch Raritan River, the reservoir is framed by the Cushetunk Mountains, which rise 500 feet above the shoreline and are composed of igneous rock, contrasting with the surrounding sedimentary formations. The park offers boating, fishing, picnicking, and a lifeguarded swimming area, and is the only New Jersey state park with wilderness camping—accessible only by a 3- to 6-mile backpacking trail or by boat.
The park is open year-round, attracting hikers in the fall for foliage, cross-country skiers and sledders in winter, and birders in spring as migratory species return to the shoreline. The Cushetunk Mountains, whose name may derive from the Lenape term for “place of hogs,” remain a prominent geological feature. Managed by the New Jersey Water Supply Authority, the reservoir primarily serves as a water supply, while the NJ Division of Fish & Wildlife oversees fish stocking and wildlife habitat.