Upper Nepean Scheme - Nepean Dam

Nepean Dam

Nepean Dam is a curved dam; it is 266 feet (81 m) tall and 710 feet (220 m) long. Construction on the Dam began in 1926, construction was delayed for two years during the Depression, it was finally completed in 1935. The capacity is listed variously as 17,898 million imperial gallons (81,360 megalitres) and 70,170 megalitres.

Railway sidings were established on the Main Southern Line at a point between Bargo and Yerrinbool. Transport to the dam site was again by light railway, on this occasion of standard gauge. This avoided transhipment from the Government vehicles bringing materials from large commercial quarries, effectively making the line an extended privately owned siding. The line was 4 km long through gentle countryside. Trains were worked by a variety of locomotives, including a former Sydney Steam Tram Motor. Additionally, there was a system of narrow (610mm) gauge lines in use at the dam construction site.

Additional work was carried out on the spillway between 1943 and 1947 to prevent scouring of the dam foundations.