Celebrating 125 Years of the Upper Nepean Scheme 125 Years
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Celebrating 125 years of the Upper Nepean Scheme 125 years s the Upper Nepean Scheme that water to Sydney to provide far away from a city, transported Acelebrates its 125th anniversary, a reliable supply. by canals and pipelines, and stored it’s remarkable that so little is known The solution that was completed in a major dam. It would also require by Sydneysiders about such an in 1888 was ingenious: two weirs no energy – water would simply important piece of infrastructure on the Upper Nepean rivers collect flow by gravity. that once saved Sydney from water which is sent by gravity It was a scheme of many firsts drought and continues to supply along a series of tunnels, canals in Australian engineering and water more than a century later. and aqueducts to a large reservoir water supply history and in this The vision for the scheme was simple in Sydney’s west, from where it flows commemorative publication yet far-sighted: collect water on the by gravity to the city and suburbs. we celebrate the remarkable Southern Highlands where it rains It was the first time in Australia achievements of those who planned, frequently and heavily, and transfer that water would be collected designed and built the scheme. Celebrating 125 years of the Upper Nepean Scheme The Upper Nepean – a scheme of firsts (Continued from front cover) Barely a decade after its completion in 1888, Sydney ran dangerously For all its simplicity and ingenuity, low on water during the Federation the Upper Nepean Scheme still drought in 1901-02. needed to be funded and constructed. It took two major government Fortunately, the scheme’s original inquiries over 13 years before funding design lent itself to progressive was allocated and work finally started expansion. As Sydney’s population in 1880. It was then built in just grew from 296,000 in 1888 to nearly eight years. 1.5 million in 1939, four new dams Engineering of the highest standard were built on the Upper Nepean to was required to build the tunnels, supplement the scheme’s supply. canals and aqueducts, because the Seventy-eight years have passed since gradient was so small and yet water the fourth dam was added to the needed to flow by gravity all the Upper Nepean Scheme, during which A scheme of firsts: way to the city. time Sydney built Warragamba Dam, • The Upper Nepean Scheme – one of the world’s largest domestic Prospect Reservoir was another Sydney becomes first Australian water supply dams. engineering feat. Not only was it city to harvest water far from Australia’s first dam with an earth fill Yet even today, the Upper Nepean the city and transfer it by canals and rock embankment, it is still an Scheme continues to supply 20 to and pipelines, and store it in a impressive example of such a 40 percent of Sydney’s water. major dam. reservoir even by today’s standards. Water continues to flow along the • Upper Canal – unique example Before the canals or the reservoir Upper Canal to Sydney, just as it did of nineteenth century hydraulic could be completed, Sydney was 125 years ago. Prospect Reservoir engineering in Australia, using again gripped by drought in 1885. remains an important part of the canal building techniques often An enterprising engineering firm water supply system. at very small grades, relying only on gravity. temporarily connected the missing And the engineers and workers who • Prospect Reservoir – Australia’s links in the scheme to provide an designed, built and maintained first earth fill and rock emergency supply of water within the scheme over the past 125 years embankment dam, and still six months (see inside story – continue to deserve our thanks for one of the largest. Hudsons’ temporary scheme). a job well done. But the story of the Upper Nepean Scheme’s ingenuity Above: The blue ribbon of the Upper Canal had only just begun. as it winds its way between Appin and Campbelltown. (Photo: A Hollingsworth) Left: Pipelines and aqueducts had to cross gullies and rivers to ensure the water could flow by gravity all the way to Prospect Reservoir. Cover image: The men who constructed Leafs Creek Aqueduct pose for the camera. This photo was taken sometime between 1886 and 1888 by renowned Australian landscape photographer Charles Bayliss and is one of the few images we have of the workers on the Upper Nepean Scheme. 125 years later, the Bayliss family connection continues with the SCA’s own Steven Bayliss, South East Operations Coordinator, overseeing Upper Canal transfers and operation of the Upper Nepean dams. Page 03 How it worked STAGE 2 – BUILT 1902-1935 STAGE 1 – BUILT BY 1888 NEPEAN SYSTEM NEPEAN RIVER NEPEAN DAM PHEASANTS NEST WEIR AVON RIVER NEPEAN RIVER AVON DAM PROSPECT RESERVOIR LOWER CANAL CORDEAUX RIVER NEPEAN TUNNEL DAM CORDEAUX DAM WEIR BROUGHTONS RESERVOIR PASS WEIR CANAL\PIPELINE TUNNEL CATARACT DAM CATARACT RIVER RIVER CATARACT UPPER CANAL TUNNEL How it worked in 1888... The entire 64-kilometre length of ...and Stage 2 open canals (44km), tunnels (19km) Rainfall on the Illawarra Plateau south Construction of the four Upper and aqueducts (1km) is known as of Sydney flows into the Cordeaux, Nepean dams between 1902 and the Upper Canal. Cataract, Avon and Nepean rivers. 1935 essentially did not alter how the From Prospect Reservoir, water flows A weir at Pheasants Nest, just below Upper Nepean Scheme worked – it by gravity along the 7.7km Lower the junction of the Cordeaux and simply increased the amount of water Canal to a basin at Guildford (known Nepean rivers, diverts some of the the scheme could reliably supply, by as Pipe Head), from where it is piped water into the 7km Nepean Tunnel storing water in upstream dams rather to a service reservoir at Potts Hill, which travels under the town of Wilton than relying solely on river flows. near Auburn. and connects with the Cataract River. Water from Avon, Cordeaux and From Potts Hills Reservoir water is A second weir on the Cataract River Nepean dams flowed to Pheasants piped to the Crown Street Reservoir, at Broughtons Pass diverts water into Nest Weir, where it was diverted via and a larger service reservoir at the 3km Cataract Tunnel. the Nepean Tunnel to Broughtons Pass Petersham. Weir. Water from Cataract Dam flowed Water emerges from the Cataract From Crown Street and Petersham directly to Broughtons Pass Weir. Tunnel into a canal at Brooks Point, reservoirs, Upper Nepean Scheme near Appin and then continues to From Broughtons Pass water flowed water is supplied to the city and flow by gravity to Prospect Reservoir. through the Cataract Tunnel and suburbs previously supplied with Upper Canal to Prospect Reservoir – water from the Botany Swamps as it did before construction of the Scheme. Upper Nepean dams. The Lower Canal was replaced with a tunnel and was decommissioned in the 1990s. The Upper Canal continues to flow by gravity, as it has done for 125 years. Celebrating 125 years of the Upper Nepean Scheme Built for our ‘health, comfort and prosperity’ ong before Warragamba Dam, Lthe Upper Nepean Scheme was the jewel in the crown of Sydney’s water supply. A Royal Commission recommended the Upper Nepean Scheme to “make Sydney the best watered of Australian cities, as it is at present the worst; and will minister to the health, comfort, and prosperity of its inhabitants to distant times”. Although the scheme needed to be expanded almost as soon as it was completed – with four major dams built in the early 1900s in addition to the two original weirs – it remains an important part of Sydney’s water supply today. Until the Upper Nepean Scheme was completed in 1888, the early settlers relied on local water supplies – originally the Tank Stream, then swamps near Centennial Park and Botany Bay. The early British settlers knew little about conserving or storing water, coming from a place where rivers always flowed and it rained all year round. Nor did they understand much about protecting the water from contamination which could also reduce the supply of drinking water. As a result the colony was regularly on the verge of running out of water. Illustration of the Upper Nepean In 1867, with a growing population, Scheme in the May 1895 ‘Town and frequent droughts, and continuing Country journal’ which celebrated public anxiety about water supplies, the transformation of Sydney’s the Governor appointed a commission water supply. to find a reliable and plentiful water supply for Sydney’s future. The five-person commission included Edward Orpen Moriarty, Engineer- in-Chief of Harbours and Rivers for the Public Works Department from 1858-88, and the man credited with the design and execution of the Upper Nepean Scheme. Edward Orpen Moriarty, Engineer-in-Chief of Harbours After two years’ investigation, the and Rivers, led the design and commission recommended collecting development of the Upper water from the 1,000 square kilometre Nepean Scheme. Page 05 Upper Nepean catchment south of Sydney, and transferring it through A daring emergency scheme to 64 kilometres of tunnels, canals and pipelines to a huge new reservoir at rescue Sydney from water famine Prospect. From there it would flow Hudsons’ Temporary Scheme by gravity along a Lower Canal to Guildford where it would connect with Before the Upper Nepean Scheme eight creeks in rugged locations and the city’s existing water supply system. could be completed, Sydney was crossing the Great Southern Railway gripped by another drought. In 1885 line near Menangle. More than a decade passed and the Lachlan and Botany swamps Even more remarkably, between the another inquiry was held before the were down to about 10 days’ supply Lower Canal at Guildford and Botany Upper Nepean Scheme was confirmed and the city council asked the they built three kilometres of open as the best solution to Sydney’s water government for urgent help.