Upper Canal
Moving water from dams south of Sydney to Prospect Reservoir.
The Upper Canal
Report any pollution to our hotline at 1800 061 069
The Upper Canal is a system of open canals, tunnels and aqueducts that moves water from four dams south of Sydney to Prospect Reservoir where it’s treated along with water from Warragamba Dam to supply Greater Sydney’s drinking water.
The four dams on the Illawarra Plateau – Cataract, Cordeaux, Avon and Nepean – are part of the Upper Nepean system that supplies up to 20% of Sydney’s drinking water.
The Upper Canal has operated continuously since 1888. As urban development continues to in-fill what was once mostly farmland in south-west Sydney, the Upper Canal is increasingly surrounded by houses and industry.
WaterNSW operates the Upper Canal, and works closely with local councils, developers, the building industry and local communities to help protect pollution entering this important water supply.
It flows through the suburbs of Kemps Creek, Austral, Leppington, Denham Court, Emerald Hills, Gledswood Hills, Gregory Hills, Currans Hill, Mount Annan, Glen Alpine.
Protecting Upper Canal from pollution
The risk of pollution entering the Upper Canal is increasing as urban development gets closer. Sediment run-off from poorly controlled building and construction sites is one of the main risks.
People who live or work nearby or who travel through the area can help by reporting any pollution or run-off entering the canal to the WaterNSW incident reporting line on 1800 061 069.
Fines of up to $44,000 apply for polluting the Upper Canal.
History and features
History of Upper Nepean scheme
The vision for the Upper Nepean scheme in the 1880s was simple yet far-sighted: collect water on the Southern Highlands where it rains frequently and heavily, and transfer that water to Sydney to provide a reliable supply.
The solution was ingenious and environmentally sustainable ahead of its time: two weirs on the Upper Nepean collect water which flows by gravity along a series of open canals (44km), tunnels (19km) and aqueducts (1km) to a large new reservoir at Prospect in Sydney’s west.
As Sydney’s population grew from 296,000 in 1888 to nearly 1.5 million in 1939, four new dams were built on the Upper Nepean to supplement the scheme’s supply.
These four dams – Cataract, Cordeaux, Avon and Nepean – continue to supply up to 20% of Sydney’s drinking water – and 135 years after it was completed, water continues to flow by gravity alone along the Upper Canal to Prospect Reservoir for the people of Sydney to drink.
A scheme of firsts
- Upper Nepean Scheme – Sydney becomes first Australian city to harvest water in an upland catchment, transfer it by canals and pipelines, and store it in a major dam.
- Upper Canal – unique example of nineteenth century hydraulic engineering in Australia, using canal building techniques often at very small grades.
- Prospect Reservoir – Australia’s first earth fill and rock embankment dam, and still one of the largest.
Features of Upper Nepean system
- Pheasant’s Nest Weir – 3 m high weir just below the junction of the Cordeaux and Nepean rivers.
- Nepean Tunnel – 7 km tunnel from the Nepean River under the town of Wilton to the Cataract River at Broughtons Pass.
- Broughtons Pass Weir – 3.5 m high weir across the Cataract River.
- Cataract Tunnel – 3 km tunnel from Broughtons Pass Weir to Brooks Point, near Appin.
- Upper Canal – 64 kms of canals, tunnels and aqueducts from Brooks Point to Prospect Reservoir.
- Prospect Reservoir – Australia’s first earth fill and rock embankment dam, designed to store 50 megalitres of water at Prospect, 35 km west of the city.
WaterNSW acknowledges the traditional custodians of the lands and waters on which we work and pay our respects to all elders past, present and emerging. Learn more