and used in the construction of the works railway to the Nepean Dam then under construction. An extensive area of Coachwood timber (Ceratopetalum apetalum) was found in the storage basin. This was cut at a special sawmill erected at the Dam and a fleet of punts and launches transported the logs down the river to the mill. About 1 million superficial feet (3,540 m3) of sawn and dressed timber was produced. It was used in the construction of buildings in the Nepean Dam township, for wall forms for both the Avon and Nepean Dams and the remainder was sold. Accommodation for workmen was provided near the construction site in a single-storey barracks for single men. Land was placed at the disposal of the married men who were assisted in constructing temporary houses for themselves and their families. Avon Dam was completed in 1927 and handed over to the Water Board on 20 January 1928. It was built at the cost of AU£1,047,000. The Dam served the Sydney area until the completion of Warragamba Dam in 1960, after which, in 1963, its storage was reserved to meet the increased water supply needs of the Wollongong area. An electrical pumping station located in Flying Fox Creek, at the end of the stored water remote from the wall, pumps water over the Divide to Wollongong and Port Kembla. In 1973, as part of a plan to interconnect the various water supply systems for Sydney, Wollongong and Sutherland, a tunnel was constructed between the Nepean Dam and the Avon Dam. This allows water to be transferred in either direction, as required. Description The Avon Dam was the third and largest of the four dams constructed to develop the Upper Nepean catchment area, in order to meet Sydney's ever increasing demand for water. It was built using cyclopean masonry. This consisted of sandstone blocks, quarried from the site, which were fitted into an irregular pattern and packed with sandstone concrete. However, in this case the rock was quarried to make a deep cut through a ridge to a neighbouring creek to provide the spillway for the dam. Like its predecessors, Avon also had the upstream face of the dam sheathed with a layer of basaltic concrete (2 feet thick) for watertightness and to resist wave and other erosion forces. The dam wall is curved in plan and has a spillway channel constructed as an open