The Chestnut Hill Reservoir Historic District is a historic district encomassing the Chestnut Hill Reservoir and the surrounding water works facilities which were historically used to provide fresh water to Boston, Massachusetts, and surrounding towns. The district is nearly coextensive with the Chestnut Hill Reservation, a state park managed by the Massachusetts Department of Conservation and Recreation (DCR); those elements of the water works that are still required as an emergency backup are managed by the Massachusetts Water Resources Authority (MWRA). The reservoir is located between Beacon Street and Commonwealth Avenue in Boston, just east of the Boston College Main Campus Historic District and the Boston-Newton city line. Most of the water works facilities are also located in Boston; the terminal house of the Sudbury Aqueduct, which is part of this district, is located just over the line in Newton.