unique within the context of dams in NSW. The four stone maintenance men cottages are likely to be rare, within the context of a non-urban environment, Federation era example of model working men's houses. The grounds of the dam contain an early 36 inch (0.9) diameter gate valve (manufacture not known) which was used to regulate the outlet flow of water which is considered the only extant example of such a valve in NSW. The upgrading works to the spillway and dam between 1981 and 1989 to make the dam meet modern day safety requirements were undertaken in consideration of the unique heritage significance of the dam in NSW ensuring no visual impact on the dam, a milestone in remedial engineering works on this scale. The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales. Cataract Dam is representative of a type of dam (cyclopean masonry gravity dam) constructed in NSW by the Water Supply and Sewerage Branch of the Public Works Department during the first half of the twentieth century. Key representative attributes of the dam's design and construction include the use of cyclopean masonry bedded in sandstone concrete, use of blue metal concrete facing, use of a spillway offset from the gravity wall, valve crest house attractively designed and finished to a high standard. The upgrading of the valves within the dam wall and ancillary monitoring and operating equipment is representative of the modern day safe operating practice. The construction technologies used at Cataract Dam came to be the norm for all subsequent dams constructed in NSW well into the twentieth century. Key representative attributes of the dam's construction techniques include the use of cableways, the building of temporary camps to house labourers and tradesman, building of semi permanent cottages to house salaried staff, the construction of terraced platforms to house plant and machinery, mechanisation of concrete production, the use of a purpose built tramway to transport raw materials from their source to the construction site, the construction of a purpose built road of access to transport men, supplies and materials from the nearest railhead to the construction site, the building of permanent infrastructure such as water supply for plant and residences, the use of electricity to power plant and equipment. The rehabilitation of tracts of land scarred in the construction process employed at Cataract Dam through