In 2020 the NSW Planning Department gave final approval for the longwall mine tunnels directly under the Reservoir to go ahead.

[2] 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.

[citation needed] Workers' accommodation was spartan but functional with small bungalows built of fibrolite and placed on brick or concrete piers on the sloping ground.

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.

[3] Six of the cottages were retained for on-site maintenance staff housing while the rest of Woronora township site was turned into picnic and recreational areas.

The 285-thousand-cubic-metre (10.1×10^6 cu ft) main wall is made from blue metal and gravel concrete and there are two inspection galleries located inside.

[1] The foundation and wall drainage systems, and the Stripped Classical architectural expression of the crest and valve houses, collectively continue to be integral elements of an Inter-war (c. 1930s) era high, curved, gravity dam in New South Wales.

The welded mild steel delivery pipeline (of which only a small section is included in the heritage curtilage) similarly represents a notable advance in construction technology for the period.

In providing water for southern suburbs of metropolitan Sydney the Woronora Dam, in ensuring security of supply, contributed to the extensive residential and commercial development of Sutherland from the 1930s.

The construction of the Dam drew upon the knowledge and experience of a number of the engineers including Gerald Haskins (the first engineer-in-chief of the former Water Board), Stanley T. Farnsworth and (Sir) William Hudson (best known for his role in the Snowy Mountains Hydro Electricity Scheme).

[1] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

Upstream of the dam wall this setting is characterised by the broad expanse of the pool of water bordered by the crests of the valley sides.

Collectively this topography at times of high water level imparts a picturesque scene when viewed from select vantage points above and on the dam wall.

as a place which is of significance to New South Wales in relation to its historical, scientific, cultural, social, archaeological, natural and aesthetic values.

[1] The grounds of the Dam are likely to be associated by members of the community with the construction township, in particular for the period of the Great Depression when considerable numbers of families who resided at the place during those turbulent years.

[1] The use of mass concrete in the upper section of the wall is likely to represent a major innovation in terms of dam construction technology at the time.

[1] The size of the dam is unusual given the primary reason behind its construction was the supply of the suburban areas south of the Georges River.

[1] The design of the spillway weir with its zig zag wall and diversion channels is likely to be unique in New South Wales for the time of construction.

[1] The crest and valve houses and inlet works retain original ironwork which represent a substantial repository of water supply delivery technology for the era.

Key representative attributes of the Dam's design and construction include the use of cyclopean masonry bedded in sandstone concrete in the lower section of wall, use of blue metal concrete in the wall facings, use of a spillway set way from the gravity wall, valve and crest houses attractively designed and finished to a high standard, the use of an array of upstream intakes to regulate the quality of water supply, the internal inspection gallery, the foundation drainage system, the contraction joints, and the drainage system.