Woronora Dam collects water from the catchment of the Woronora River, which drains into the dam and then to Georges River. The dam supplies water to residents within the Sutherland Shire in Sydney's south and also the northern Illawarra suburbs of Helensburgh, Otford, Stanwell Tops, Stanwell Park and Coalcliff.
Woronora Dam is curved in appearance and is a mass gravity dam, remaining in position under its own weight. Its lower levels are built of cyclopean masonry - massive sandstone blocks that were quarried on site. The main wall is made from blue metal and gravel concrete and there are two inspection galleries located inside.