Cataract Dam wall
|Location||Cataract Road, Appin, New South Wales|
|Purpose||Potable water supply|
|Built by||Ernest Macartney de Burgh|
|Operator(s)||Sydney Catchment Authority|
|Dam and spillways|
|Type of dam||Gravity dam|
|Height||56 m (184 ft)|
|Length||247 m (810 ft)|
|Dam volume||112×103 m3 (4.0×106 cu ft)|
|Spillway capacity||1,550 m3/s (55,000 cu ft/s)|
|Total capacity||94,300 ML (2.07×1010 imp gal; 2.49×1010 US gal)|
|Catchment area||130 km2 (50 sq mi)|
|Surface area||8,500 ha (21,000 acres)|
|Official name||Cataract Dam|
|Criteria||a., b., c., d., e., f., g.|
|Designated||18 November 1999|
|Part of||Utilities - Water group|
The Cataract Dam, one of four dams and weirs in the catchment of the Upper Nepean Scheme, in New South Wales, Australia, provides water to the Macarthur and Illawarra regions, the Wollondilly Shire, and metropolitan Sydney. Completed in 1907 under the supervision of Ernest Macartney de Burgh, the dam is currently managed by the Sydney Catchment Authority and is listed on the NSW State Heritage Register.
A gravity dam with an unlined side spillway extending from the left abutment, it is 56 metres (184 ft) tall; 247 metres (810 ft) long; and it holds 94,300 megalitres (20.7×109 imp gal; 24.9×109 US gal) of water. Cataract Dam was the first dam built in the Upper Nepean Scheme. It was also first dam in Australia to use pre-cast moulded concrete blocks for the upstream face of the dam. The downstream face is of mass poured basalt concrete, with a basalt facing. A readily accessible source of suitable rock was located at Sherbrooke, situated near the top of Bulli Pass. To transport the basalt from the quarry to the dam construction site, a 2 ft (610 mm) gauge steam tramway, 8.8 kilometres (5.5 mi) long, was constructed.
The dam is built of cyclopean masonry, composed of sandstone blocks weighing from 2 to 4.5 long tons (2.03 to 4.57 t; 2.24 to 5.04 short tons). These were quarried at the site and bedded in cement mortar. The vertical joints were filled with basalt or sandstone concrete. The upstream face consisted of basalt concrete moulded blocks set in a cement mortar. The downstream face was of basalt concrete, 1.8 metres (5 ft 11 in) thick in the lower section and 0.9 metres (2 ft 11 in) thick in the upper section. There were two lines of 122-centimetre (48 in) diameter pipes which passed through the dam and discharged water into the Nepean River. The flow is controlled by a Larner Johnson needle valve. The dam wall was given a decorative finish. The upstream parapet was castellated with sandstone blocks while the top of the downstream wall was corbelled in concrete. In approximately the midsection of the dam stands the valve house. This is finished in quarried sandstone blocks with ashlar coursing. It features a steeply pitched slate-covered pipped roof topped with finials and gables at either side.
Dam construction began in 1902 and was completed in 1907, and the spillway was widened in 1915. E. M. de Burgh was the supervising engineer for the project from 1904.
The Upper Nepean Scheme was commenced in 1880 after it was realised that the Botany Swamps scheme was insufficient to meet Sydney's water supply needs. The Nepean project consisted of the construction of a weir across the Nepean River to divert of the rivers Cataract, Cordeaux, Avon and Nepean, to the Prospect Reservoir.
The design and construction of Cataract Dam was undertaken by the Water Supply and Sewerage Branch and Harbour and Rivers Branch of the New South Wales Public Works Department. The construction of the dam necessitated the knowledge and experience of a number of engineers employed in the branches at the time including Cecil Darley (NSW Inspecting Engineer in London), Leslie Wade (Principal Engineer, Water Supply and Sewerage Branch), Henry Dare and Ernest M. de Burgh (Supervising Engineers). The successful completion of the dam and its continuation of use as a water supply dam are a lasting testament to the professional capabilities of the late Victorian/Edwardian era generation of engineers of the Public Works Department. The association of Thomas Keele with the initial dam proposal, and the subsequent problems associated with the cost and the ongoing Royal Commissions into the project was immortalised through Banjo Paterson's satirical ballad The Dam that Keele Built.
Cataract Dam was the first of the four water supply dams built as part of the development of the Upper Nepean Water Supply Scheme, one of the most important engineering works and items of public infrastructure in Australia. Cataract Dam was designed by engineers of the Public Works Department under direction of two of Australia’s leading water supply engineers, L.A.B. Wade, Chief Engineer for Water Supply and Sewerage and E.M. De Burgh, who was Supervising Engineer.
The completion of Cataract Dam was a significant step in the continuing process of providing a reliable water supply for Sydney and surrounding areas and was part of a process of development of the Upper Nepean Scheme which was envisaged when that Scheme was designed in the 1880s. Cataract Dam was the largest dam constructed in NSW at the time and was considered to be a significant work of engineering in its day. It continues to play an important role as a major source of water supply for the Sydney area. Additionally, the Cataract Dam is a handsome, well proportioned structure with strong Tudor style architectural character which complements the monumental nature of the structure and its attractive natural surroundings.
Cataract Dam includes a range of ancillary structures which form components of the overall site, including a set of handsome sandstone masonry residential cottages for operational staff (which appear to date from the construction of the dam). They are representative of their age and type.
The Official Quarters is a particularly fine example of a Federation Queen Anne Bungalow, with matching outbuildings and landscaped gardens and is associated with the accommodation of both the senior engineers of the Public Works Department and the Governor of NSW at the opening of the Dam. The Residential Engineers Cottage is also a fine quality building dating from the 1960s.The Dam surrounds include remnants of its early 20th century gardens, evidence of a high level of landscape design awareness through its planning and detailing, and extensive areas of bushland. Individual components of its remnant gardens, such as its main (upper level) grotto shelter and ornamental follies, are rare in NSW on account of their imaginative conception and quality of craftsmanship. The extensive scale of the remnant area of public parklands is notable and that they continue to attract regular visitation since their opening indicates that the place is highly regarded. The immediate environment around the dam wall - including the key engineering structures and associated architecture, the upstream body of water, the downstream gorge and surrounding vegetation - forms a localised cultural landscape of scenic distinction.— Statement of significance, New South Wales State Heritage Register.
- "Register of Large Dams in Australia" (Excel (requires download)). Dams information. Australian National Committee on Large Dams. 2010. Retrieved 11 March 2014.
- Longworth, Jim (July 1993). "Construction Railways of the Upper Nepean Dams - Cataract Dam". Australian Railway Historical Society Bulletin: 163–174.
- "Cataract Dam". New South Wales State Heritage Register. Office of Environment and Heritage. Retrieved 13 April 2012.
- Antill, J. M. (1981). "De Burgh, Ernest Macartney (1863 - 1929)". Australian Dictionary of Biography. Melbourne University Press. p. 266. Retrieved 22 April 2007.