Boulder’s Hidden Gross Reservoir: The Mountain Lake Most Visitors Miss
Drive west from downtown Boulder on Flagstaff Road and the city quickly falls away. Pines close over the pavement, mountain views appear between the trees and the road eventually becomes Gross Dam Road. Then the canyon opens onto a long, dark reservoir tucked between granite walls.
This is Gross Reservoir: 440 acres of cold mountain water, nearly 11 miles of shoreline and a spillway elevation of 7,282 feet. Although it sits within Boulder County, it is not Boulder’s municipal reservoir. Denver Water owns and operates it.
Swimming and wading are prohibited, and motorized boats—including electric motors—are not allowed. There is no developed swimming beach, marina or resort infrastructure. Those limitations have helped Gross remain one of the area’s more secluded public waters and another remarkable part of Boulder’s mountain landscape…