Definition
Tallowa Dam is a concrete gravity dam with a central overflow spillway on the Shoalhaven River in New South Wales, Australia. It creates the reservoir known as Lake Yarrunga and forms part of the Shoalhaven water‑supply scheme.
Overview
Construction of the dam began in 1972 by Leighton Contractors and was completed in 1976. The dam is owned by the Sydney Catchment Authority and operated by WaterNSW. Its primary purposes are water supply for Sydney, the Illawarra region, and local communities in the Shoalhaven and Kangaroo Valley areas, as well as the provision of environmental flow releases to maintain downstream river health.
Etymology/Origin
The name “Tallowa” is derived from the locality in which the dam is situated, near the junction of the Kangaroo and Shoalhaven Rivers. The term is of Aboriginal origin, though specific linguistic roots are not definitively documented in publicly available sources.
Characteristics
- Type: Concrete gravity dam
- Height: 43 m (141 ft)
- Length: 518 m (1,699 ft)
- Dam volume: 325 m³ (≈11,500 ft³)
- Spillway: Single central overflow spillway with a capacity of 27,600 m³ s⁻¹ (≈970,000 ft³ s⁻¹)
- Reservoir (Lake Yarrunga):
- Surface area: 831 ha (2,050 acres)
- Total storage capacity: ~90 000 ML (≈3.2 billion ft³)
- Active (transferable) storage for Sydney water supply: ~21 800 ML (≈770 million ft³)
- Catchment area: 5 750 km² (2 220 sq mi)
- Fish passage: An innovative fish lift installed in 2009 enables migratory native fish to bypass the dam wall, addressing the barrier created by the structure.
Related Topics
- Shoalhaven River – the river on which the dam is built.
- Lake Yarrunga – the reservoir impounded by Tallowa Dam.
- Sydney water supply system – the broader network of dams and pipelines serving the metropolitan area.
- Fish lifts and fishways – engineering solutions for maintaining aquatic fauna connectivity across dams.
- Concrete gravity dams – a class of dams that rely on their weight to resist hydraulic forces.
All information is sourced from publicly available encyclopedic references, including the Wikipedia entry for Tallowa Dam and WaterNSW documentation.