The Upper Nepean Scheme is a series of

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

s and

weir A weir or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the water level. Weirs are also used to control the flow of water for outlets of l ...

s in the catchments of the

Cataract A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...

, Cordeaux, Avon and Nepean rivers of

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. The scheme includes four dams and two weirs, and a gravity-fed canal system that feeds into a large storage

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

to provide water to the Macarthur and

Illawarra The Illawarra is a coastal Regions of New South Wales, region in the southeast of the Australian state of New South Wales. It is situated immediately south of Sydney and north of the South Coast, New South Wales, South Coast region. It encompas ...

regions, the

Wollondilly Shire Wollondilly Shire is a Peri-urbanisation, periurban Local government in Australia, local government area that is located on the far southwest fringe of the Sydney, Greater Sydney area in New South Wales, Australia. The local government area is pa ...

, and metropolitan

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

. The four dams and associated infrastructure are individually listed on the

New South Wales State Heritage Register The New South Wales State Heritage Register, also known as NSW State Heritage Register, is a heritage list of places in the state of New South Wales, Australia, that are protected by New South Wales legislation, generally covered by the Heritag ...

History

By 1867, Sydney was outgrowing the water supply available from Botany Swamps and the

Governor A governor is an politician, administrative leader and head of a polity or Region#Political regions, political region, in some cases, such as governor-general, governors-general, as the head of a state's official representative. Depending on the ...

( Sir John Young) appointed a Commission to recommend a future water supply. In 1869, the Commission recommended the Upper Nepean Scheme. This comprised weirs on the Cataract and Nepean rivers, a storage reservoir at Prospect and of pipelines, tunnels, canals and aqueducts to bring water from the catchment area to Sydney. Work on the Scheme began in 1880 and was completed in 1888. The Scheme was a significant feat of engineering at the time of construction. In June 1885 Sydney was in the grip of a severe drought and the Upper Nepean Scheme was incomplete. The Government accepted an offer from Hudson Brothers to bridge the gaps and deliver of water per day into Botany Swamps. Duplicating the entire length of the half built permanent scheme this became known as Hudsons' Temporary Scheme and was turned into the swamps on 30 January 1886. This emergency work was dismantled as the main scheme was completed. As originally built, the Upper Nepean Scheme was capable of supporting an estimated population of 540,000. By 1902, Sydney had a population of 523,000 and was again in the grip of a severe drought. A Royal Commission appointed to report on Sydney's water supply recommended a dam on the Cataract River and construction commenced in the same year. Dams were subsequently built on each of the Cordeaux, Avon and Nepean rivers, with the last being completed in 1935. Each dam includes a public picnic area. In total, the four dams hold and can safely provide per day. The Scheme is now managed by the Sydney Catchment Authority. Further supplementary water supply is provided by a feed from the Shoalhaven Scheme through various pumps, pipes, cuts and diversions.

Associated dams

Cataract Dam

The Cataract Dam is a heritage-listed

gravity dam A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation. Gravity dams are designed so that each section of the dam is ...

with an unlined side spillway extending from the left abutment. It is tall, long and holds 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 core of the dam consists of large sandstone blocks, quarried onsite and

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

ed together. The downstream face is of mass poured basalt concrete, with a

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

facing. A readily accessible source of suitable rock was located some distance away at Sherbrooke, also known as Ferndale, situated near the top of Bulli Pass. To transport the basalt from the quarry to the dam construction site, a gauge steam tramway, long, was constructed. Dam construction began in 1902 and was completed in 1907, and the spillway was widened in 1915. Ernest Macartney de Burgh was the supervising engineer for the project from 1904. Poet

Banjo Paterson Andrew Barton "Banjo" Paterson, (17 February 18645 February 1941) was an Australian bush poet, journalist and author, widely considered one of the greatest writers of Australia's colonial period. Born in rural New South Wales, Paterson worke ...

wrote a satirical ballad "The Dam that Keele Built" about the politics behind the construction of Cataract Dam.

Cordeaux Dam

The Cordeaux Dam is a heritage-listed

arch dam An arch dam is a concrete dam that is curved upstream in plan. The arch dam is designed so that the force of the water against it, known as hydrostatic pressure, presses against the arch, causing the arch to straighten slightly and strengtheni ...

across the Cordeaux River with an unlined side spillway on the left abutment. It is high, long and creates a reservoir which holds . Construction began in 1918 and was completed in 1926 at a cost of A£945,000. The wall consists of large sandstone blocks, quarried onsite and cemented together, faced with a combination of bluestone and sandstone concrete. The dam featured a number of improvements in design and construction on the earlier-completed Cataract Dam. These included contraction joints between units of construction placed at intervals of ; inspection galleries at upper and lower levels, together with piping for registering any ground water pressure. The blue metal used in the construction of the dam was supplied from the Government Quarries at

Kiama Kiama may refer to: * Electoral district of Kiama, a seat in the New South Wales Legislative Assembly * Kiama, New South Wales, a town * Kiama (spider), a genus of spiders *Municipality of Kiama The Municipality of Kiama is a local government ar ...

and brought by rail to Douglas Park. From here it was conveyed by aerial ropeway across the Nepean Gorge to an interchange on the eastern side where the material was transferred to a gauge steam tramway to a point adjacent to the dam site.

Avon Dam

The Avon Dam is a heritage-listed arch dam across the Avon River; it is tall, long and its reservoir holds . It has the largest capacity of all the dams in the Scheme. Construction of the heritage-listed dam wall began in 1921 and was completed in 1927 at a cost of A£1,047,000. The dam construction and materials are the same as Cordeaux. All materials for construction were transported from Bargo railway station on a specially built road, all the other dams in the scheme used rail transport. There were some light tramways constructed at the dam site, however it would appear that no locomotives were employed; skips and other items being moved by winch, horse or manpower.

Nepean Dam

The Nepean Dam is a heritage-listed arch dam across the

Nepean River The Nepean River (Darug language, Darug: Yandhai), is a Perennial stream, major perennial river, located in the south-west and west of Sydney, New South Wales, Australia. The Nepean River, and, continuing by its downstream name, the Hawkesbury ...

; it is tall and long. Construction on the Dam began in 1926, construction was delayed for two years during the Depression, it was finally completed in 1935. The capacity is listed variously as . The Nepean Reservoir has a small storage capacity in relation to its large catchment area of . While its capacity is much the same as that of Cataract and Cordeaux Reservoirs, its catchment basin is two and a half times as extensive as Cataract and three and a half times as extensive as Cordeaux. The Nepean Reservoir therefore fills more rapidly and, under normal conditions, is drawn upon more freely than the other reservoirs. The dam is located at an elevation of

above sea level Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level ...

and the construction cost was A£2,062,000. Railway sidings were established on the Main Southern railway line at a point between Bargo and Yerrinbool. Transport to the dam site was again by light railway, on this occasion of standard gauge. This avoided transhipment from the Government vehicles bringing materials from large commercial quarries, effectively making the line an extended privately owned siding. The line was long through gentle countryside. Trains were worked by a variety of locomotives, including a former Sydney Steam Tram Motor. Additionally, there was a system of narrow () gauge lines in use at the dam construction site. Additional work was carried out on the spillway between 1943 and 1947 to prevent scouring of the dam foundations.

Gallery

Image:Cataract_at_capacity.jpg, Cataract reservoir at full capacity, discharging through spillway Image:Cataract_spillway.jpg, Detail of Cataract Dam spillway Image:Cataract_outlet_works.jpg, Outlet works at Cataract Dam Avon Dam plate.jpg, Avon Dam plate Nepean Dam plate.jpg, Nepean Dam plate

References

Attribution

This Wikipedia article was originally based on th
''"New South Wales State Heritage Register"''
published by the

Government of New South Wales The Government of New South Wales, also known as the NSW Government, is the executive state government of New South Wales, Australia. The government comprises 11 portfolios, led by a ministerial department and supported by several agencies. Th ...

unde
CC-BY 3.0 AU
licence (accessed on 13 April 2012); and based on th
''"New South Wales State Heritage Register"''
published by the

unde
CC-BY 3.0 AU
licence (accessed on 29 September 2017); and based on th
''"New South Wales State Heritage Register"''
published by the

unde
CC-BY 3.0 AU
licence (accessed on 29 September 2017).