Why it was built

Why it was built

Edward Moriarty

Edward Orpen Moriarty, Engineer-in-Chief of Harbours and Rivers, led the
design and development of the Upper Nepean Scheme.

Long before Warragamba Dam, the 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.

In 1867, with a growing population, frequent droughts, and continuing public anxiety about water supplies, the Governor appointed a commission 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.  After two years' investigation, the commission recommended collecting water from the 1,000 square kilometre Upper Nepean catchment south of Sydney, and transferring it through 64 kilometres of tunnels, canals and pipelines to a huge new reservoir at Prospect. From there it would flow by gravity along a Lower Canal to Guildford where it would connect with the city's existing water supply system.  More than a decade passed and another inquiry was held before the Upper Nepean Scheme was confirmed as the best solution to Sydney's water needs, and work finally began in 1880.

Then in 1885, before the scheme was completed, Sydney was gripped by another major drought. With only 10 days' supply remaining, urgent action was required (see 'Daring emergency scheme').

In 1888, the first stage of the Upper Nepean Scheme was completed and water finally flowed from the Upper Nepean weirs along the Upper Canal to Prospect Reservoir to supply the city's needs.

That same year the Board of Water Supply and Sewerage was established to manage all water supply and sewerage infrastructure owned by government and city councils.  Today, Sydney Water manages treated water supply and sewerage. The Upper Nepean Scheme and Sydney's other major dams and raw water supply infrastructure are managed by WaterNSW.

As for the Upper Nepean Scheme, 130 years after it was completed its legacy continues as a valuable part of Sydney's water supply.  Indeed, the Upper Nepean Scheme has lived up to predictions that it "will minister to the health, comfort, and prosperity of its inhabitants to distant times".


Wednesday 27 January
2,392,415 ML
2,581,850 ML
11,945 ML
1,707 ML
-12,079 ML
Wednesday 27 January