Upper Nepean Scheme
The scheme includes four dams and two weirs, and a gravity-fed canal system that feeds into a large storage reservoir to provide water to the Macarthur and Illawarra regions, the Wollondilly Shire, and metropolitan Sydney.
The Government accepted an offer from Hudson Brothers to bridge the gaps and deliver 14 megalitres; 3.6 million US gallons (3×10^6 imp gal) of water per day into Botany Swamps.
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.
Further supplementary water supply is provided by a feed from the Shoalhaven Scheme through various pumps, pipes, cuts and diversions.
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.
These included contraction joints between units of construction placed at intervals of 27 metres (90 ft); inspection galleries at upper and lower levels, together with piping for registering any ground water pressure.
[2] The blue metal used in the construction of the dam was supplied from the Government Quarries at Kiama 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 2 ft (610 mm) gauge steam tramway to a point adjacent to the dam site.
[14] 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.
[18][8]: 268 The Nepean Reservoir has a small storage capacity in relation to its large catchment area of 319 square kilometres (123 sq mi).
This avoided transhipment from the Government vehicles bringing materials from large commercial quarries, effectively making the line an extended privately owned siding.
Additionally, there was a system of narrow (610 mm / 2 ft) gauge lines in use at the dam construction site.
