these dams to have been completed. The Upper Nepean Catchment Area continues to supply the regions of Sydney and Illawarra. Cordeaux Dam was the fourth of the major water supply dams constructed in NSW during the first half of the twentieth century. The design and technologies used in the construction of the dam are representativethe methods developed by the Public Works Department of NSW at the time. In conjunction with the completion of Avon Dam in 1927, the impounded water of the Cordeaux catchment area provided one of the major sources of water for domestic and industrial consumption in metropolitan Sydney, the largest city in New South Wales. 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 1920s and 1930s. The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history. The design and construction of Cordeaux Dam was undertaken by the Water Supply and Sewerage Branch of the NSW Public Works Department. The construction of the dam drew upon the knowledge and experience of a number of engineers employed in the Branch at the time, including Ernest M. de Burgh (Chief Engineer). The successful completion of the dam and its continuation of use as a water supply dam are a lasting testament to the professional capabilities of the Federation/Inner War era generation of engineers of the Public Works Department. The tract of Eucalyptus bordering the encircling road of the upper picnic area was planted out by Board members of the former Water Board in 1928. The trees have particular memorial associations with past identities of the Board. The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales. The wall of Cordeaux Dam is an engineering work imbued with a sense of aesthetic values expressed through the long curved wall set within the valley of the Cordeaux River. The design and finishes of the crest houses, entry pylons and lower valve houses in the Inter Egyptian style were undertaken by the Government Architect's branch of the Public Works Department at the time headed by George McCrae. The architectural detailing evokes a romanticised version of the Ancient Near East at a time when many