 Built between 1882 and 1888, it was an outstanding achievement in civil engineering technology at the time, using innovative design and construction methods.It has a high level of historical engineering significance.Prospect Reservoir is strongly associated with the Harbours and Rivers Branch of the NSW Public Works Department, particularly Edward Orpen Moriarty, Head of the branch at the time of the Reservoir's construction, and later with the Board of Water Supply and Sewerage (later the Metropolitan Water and Sewerage Board) and most recently, with the Sydney Catchment Authority.