The Woronora Dam is a heritage-listed concrete gravity dam with an uncontrolled serpentine spillway across the Woronora River, located south of Greater Metropolitan Sydney, in the suburb of Woronora Dam, Sutherland Shire, 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 reservoir is also called Woronora Dam and is sometimes incorrectly called Lake Woronora. The dam was designed by G. E. Haskins, Chief Engineer and the Metropolitan Water, Sewerage and Drainage Board of NSW (MWS&DB) and built from 1927 to 1941 by the MWS&DB. The property is owned by the Sydney Catchment Authority, an agency of the Government of New South Wales. It was added to the New South Wales State Heritage Register on 18 November 1999. In 2009 the NSW State government granted the mining company Peabody conditional approval to mine for coal in the Reservoir catchment and directly under the Reservoir. In 2020 the NSW Planning Department gave final approval for the longwall mine tunnels directly under the Reservoir to go ahead. History Water was first supplied to the Sutherland Shire in 1911 when a 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 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