Nepean Dam, Concrete-face rock-fill dam in New South Wales, Australia

Nepean Dam is a concrete-face rock-fill dam in New South Wales that rises 82 meters high and stretches 216 meters wide. The structure combines large sandstone blocks embedded within concrete in a stable and efficient design.

Construction of Nepean Dam began in 1925, after the 1918 Board of Experts recommended supplementing the Cataract and Cordeaux dams. The Public Works Department started the work under E. M. de Burgh; from 1 September 1928 the Board of Water Supply and Sewerage continued it. Work was suspended in March 1930 during the Depression, resumed on 12 June 1933, and the dam was completed in 1935.

The area around the dam preserves residential cottages that reveal how people lived here across different eras and how the infrastructure evolved over time. These buildings reflect the changing needs of the communities that managed this water system.

The dam collects water from a large catchment area and supplies drinking water to Sydney, Macarthur, and Illawarra regions. Visitors can explore the site and see the engineering work up close.

The dam system expanded in the 1960s with connecting tunnels that allowed more efficient water distribution across the network. These underground structures represent early innovations in regional water engineering.