its top is . It remains in everyday use for the purpose for which it was designed. It is built of concrete (not reinforced), curved in plan, with reliance for stability being placed only on the capacity of the material in the wall and sides of the valley to resist compression. Associated with the dam is a small corrugated iron clad pumping shed, which contained three pumps. In 1993, these were rated as being of some significance, with two dating from 1927 and the third from the mid-1930s. Condition As at 24 September 2008, the Medlow Dam is intact and in good condition. Modifications and dates 1993 - Calcite deposits were removed from the downstream face using high pressure water jets. 2008 - Trunnion winch was replaced and the original winch moved to the side of the carpark for interpretive purposes. Heritage listing As at 26 August 2009, the Medlow Dam was the first of the water supply dams built as part of the development of the Upper Blue Mountains and is an important example of the "Wade" series of dams erected in NSW between the 1890s and early 1900s for NSW country town water supplies which utilised a concrete arch wall. It is associated with the NSW Department of Public Works and its design is a product of the work of two of Australia's leading engineers, L. A. B. Wade and C. W. Darley. The Medlow Dam was a world leader in the development of thin-walled concrete arch dams and created considerable controversy when completed, reputedly having the thinnest wall of any comparable dam in the world. It remains a textbook example of this form of design and construction. The completion of the Medlow Dam was a significant step in the process of providing a reliable water supply for Medlow Bath, Blackheath and the surrounding areas. Medlow 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. The Medlow Dam was the first of the water supply dams built as part of the development of the Upper Blue Mountains and was an important example of the "Wade" series of dams erected in NSW between the 1890s and early 1900s for NSW country town water supplies which utilised a concrete arch