Tallowa Dam

Tallowa Dam
The Tallowa Dam spillway, 2010
Status	Operational
Opening date	1976
Dam and spillways
Type of dam	Gravity dam
Impounds	Shoalhaven River
Height	43 m (141 ft)
Length	518 m (1,699 ft)
Dam volume	325 m3 (11,500 cu ft)
Spillways	1
Spillway type	Central overflow
Spillway capacity	27,600 m3/s (970,000 cu ft/s)
Reservoir
Creates	Lake Yarrunga
Total capacity	90,000 ML (3,200×10^6 cu ft)
Catchment area	5,750 km2 (2,220 sq mi)
Surface area	831 ha (2,050 acres)
Website Tallowa Dam at www.sca.nsw.gov.au

Tallowa Dam, completed in 1976, is a concrete gravity dam with central overflow spillway, located of the Shoalhaven River, downstream from the river's confluence with the Kangaroo River. The dam wall of 325 cubic metres (11,500 cu ft) is 43 metres (141 ft) high and 528 metres (1,732 ft) in length. At 100% capacity, the dam wall holds back approximately 85,500 megalitres (3,020×10^⁶ cu ft) and creates the impounded reservoir of Lake Yarrunga that has a surface area of 831 hectares (2,050 acres), drawn from a catchment area of 5,750 square kilometres (2,220 sq mi). The spillway has a discharge capacity of 27,600 cubic metres per second (970,000 cu ft/s).

The 'full operating storage' for Tallowa Dam refers only to the amount of water in the dam that is available to be transferred to Sydney and the Illawarra. When full, the dam can hold approximately 90,000 megalitres (3,200×10^⁶ cu ft) but only 7,500 megalitres (260×10^⁶ cu ft) is available to be transferred to the Sydney water supply. Other water from Tallowa Dam is provided to Shoalhaven City Council for supply to local communities. Water is also released from the dam as environmental flows for the Shoalhaven River.