remnant road borders and evidence of buildings visible on the ground. The public area has been maintained by the Water Board and its successors, with picnic grounds, landscaped gardens and a children's playground. Remnants of the interwar period landscape at the Nepean Dam site are mainly concentrated in two areas - around a small park, with cement faux rockwork bedding edges, to the east of the dam wall, including a long line of Roman Cypress (Cupressus sempervirens) along the spillway alignment; and in a park-like picnic area along a terrace above the dam. Features of the latter area include pleasant plantings of mixed deciduous and evergreen exotic trees and Australian trees enclosing a long raised shelf, which is the remnant railway platform from the temporary construction railway, with a series of small timber picnic shelters with a somewhat log cabin-style character. Nearby a considerable line of dry-packed sandstone walling has been used and drystone walling is used generally to control access. The main entry road includes the remains of an old Cypress avenue and an ornamental gum avenue. Heritage listing Nepean Dam was the fourth of the four water supply dams built as part of the development of the Upper Nepean Water Supply Scheme, one of the most important engineering works and items of public infrastructure in Australia, and had the highest wall of all the NSW water supply dams at the time of its construction. It was designed by the NSW Public Works Department under the direction of one of Australia's leading water supply engineers, E.M. de Burgh. The completion of the Nepean Dam was a significant step in the continuing process of providing a reliable water supply for Sydney and surrounding areas as part of the Upper Nepean Scheme. Even by the international standards of the time, Nepean was a large dam and was a significant work of engineering in its day. It continues to play an important role as a major source of water supply for the Sydney region. Additionally, the Nepean Dam is a handsome, well proportioned structure with strong Stripped Classical style architectural character which complements the monumental nature of the structure and its attractive natural surroundings. Nepean Dam includes a range of ancillary structures which form components of the overall site, including residential cottages of various ages for operational staff and are representative of their age and type. The former Resident Engineer's cottage is