Woronora Reservoir

Woronora Dam
Aerial view of Woronora Dam reservoir
Location of the Woronora Dam in New South Wales
Country	Australia
Location	south of Sydney, New South Wales
Coordinates	34°6′40″S 150°56′4″E / 34.11111°S 150.93444°E / -34.11111; 150.93444Coordinates: 34°6′40″S 150°56′4″E / 34.11111°S 150.93444°E / -34.11111; 150.93444
Status	Operational
Construction began	1927
Opening date	1941
Construction cost	A$13 million
Owner(s)	Sydney Catchment Authority
Dam and spillways
Type of dam	Gravity dam
Impounds	Woronora River
Height	66 m (217 ft)
Length	390 m (1,280 ft)
Dam volume	285×10^3 m3 (10.1×10^6 cu ft)
Spillway capacity	1,470 m3/s (52,000 cu ft/s)
Reservoir
Creates	Woronora Dam
Total capacity	71,790 ML (2,535×10^6 cu ft)
Catchment area	75 km2 (29 sq mi)
Surface area	380 ha (940 acres)

The Woronora Dam is a concrete gravity dam with an uncontrolled serpentine spillway across the Woronora River, located south of Greater Metropolitan Sydney, in New South Wales, Australia. The principal purpose of the dam is for potable water supply for Sydney's southern suburbs and the northern suburbs of the Illawarra region. The impounded 71,790-megalitre (2,535×10^⁶ cu ft) reservoir is also called Woronora Dam and is sometimes incorrectly called Lake Woronora.

Water was first supplied to the Sutherland Shire in 1911 when a 150-millimetre (5.9 in) pipe was laid from Penshurst Reservoir across Georges River at Tom Ugly's Point to Miranda. In 1920 a scheme to supply water from the Woronora River to Sutherland and Cronulla was rejected. It was resurrected five years later when the then Metropolitan Water Sewerage and Drainage Board became the sole constructing authority for water supply works in the metropolitan area. The scheme involved the construction of a dam, which could be increased in size if necessary, on the Woronora River, about 24 kilometres (15 mi) upstream of its junction with the Georges River.

Construction of the dam began in 1927, the fifth dam built as part of Sydney's water supply. As forecast, the size of the dam wall had to be increased two years later. Workers' accommodation was spartan but functional with small bungalows built of fibrolite and placed on brick or concrete piers on the sloping ground. In 1930 The Depression intervened, suspending work on the dam. The men were forced to look for work further afield, even interstate, often leaving their families behind to live on the Woronora site. Some families had strong ties to the history of Sydney's dams, moving from the Nepean Dam project to Woronora, and then onto Warragamba. Other workers on Woronora Dam were former coal miners from nearby Helensburgh. Late in 1931 the Unemployment Relief Account released funds to build a weir to provide water to the Sutherland-Cronulla area and four years later, work resumed on the dam itself.