an attractive example of a vernacular cottage of the early twentieth century. The public picnic grounds include a former construction railway platform now housing picnic shelters, and the site of the original construction village remains undeveloped and is now an overgrown archaeological site. The Nepean Dam picnic areas and gardens contain a cultural landscape resource - including remnants of its interwar period plantings, layout and detailing, and extensive areas of bushland - of regional value. The finely detailed dam structures of large-scaled concrete in Art Deco-style sit within a broader landscape setting of outstanding scenic quality. Nepean Dam was listed on the New South Wales State Heritage Register on 18 November 1999 having satisfied the following criteria. The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales. Nepean Dam is located within the Upper Nepean Catchment Area which was developed with the completion of the Cataract and Nepean Tunnels in 1888, as the fourth source of water supply for Sydney. The potential of the Upper Nepean Catchment Area to supply water was fully developed through the construction of four major dams between 1903 and 1936. Nepean Dam is the last of these dams to have been completed. The Upper Nepean Catchment Area continues to supply the regions of Sydney and Illawarra, with the Nepean Dam providing a supply to Sydney, Macarthur, Bargo and Illawarra (through the Avon/Nepean Tunnel) regions. Nepean Dam was the fifth of the major water supply/irrigation dams constructed in NSW during the first half of the twentieth century. Whilst the dam was designed by the Public Works Department of NSW, the technologies used in the dam are representative of methods developed by that authority, the planning and scale of the construction techniques are more representative of the Water Board. In conjunction with other Metropolitan Dams and Woronora Dam built in 1941, the impounded water of Nepean Dam provided one of the major sources of water for domestic and industrial consumption in metropolitan Sydney, the largest city in NSW. In providing water for metropolitan Sydney during this era the dam, in ensuring security of supply, contributed to the extensive residential, commercial and industrial development of Sydney during the 1930s and 1950s. Nepean Dam was constructed over a period of ten years between 1926 and 1936, a protracted construction period which is directly related to the Great Depression and a