Work on Nepean Dam started in 1925. It wasinterrupted for a few years by the Depressionbut resumed in 1933. Materials were hauled on a standard gauge railway line from the mainsouthern line near Bargo.

The dam was finally completed in 1935 and costabout $12.3 million.

After several years of extremely low rainfall inthe catchment, heavy rainfall in October 1938saw the dam finally reach capacity and overflowvia its stand–alone crest level spillway.

A tunnel linking Avon and Nepean dams toenable transfer of water between the dams ineither direction was completed in 1973.

Nepean Dam was strengthened in 1992 bypost–tensioned anchors and a downstreamrockfill embankment. It was furthersafeguarded by the addition of a concrete–linedside spillway on the right abutment in 1992.

Height: 82 metres Length: 216 metresTotal capacity: 70,170 megalitresCatchment: 320 square kilometres Lake: 3.3 square kilometres

Nepean Dam

All the Upper Nepean dams were constructedby the Public Works Department for theMetropolitan Water Sewerage and DrainageBoard. They are all mass gravity dams,remaining in position under their own weight.They were the first dams in Australia ofcyclopean masonry construction, an earlymasonry style using massive stone blocks. The sandstone blocks used weighed between 2 and 4.5 tonnes, and were quarried on site.

Following the construction of Cataract Dam,improvements in design and engineering led toseveral new features including inspectiongalleries, piping to register groundwaterpressure, and upper and lower level dischargeoutlets for the later Upper Nepean dams.

Constructing the Upper Nepean dams

MASSIVE SANDSTONEBLOCKS USED IN DAMWALL CONSTRUCTION< NEPEAN DAM

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SOCIAL LIFE THEN AND NOW AT THE DAMS

During the construction of the Upper Nepeandams temporary townships were establishedon each construction site. Married employeesand their families rented the cottages whilesingle men were accommodated in barracks.

With the completion of each dam, thetownship structures were moved on to thenext work site or were sold for demolition or removal. The grounds were turned intogarden parklands with picnic andrecreational facilities.

Some families spent their whole lives atthese dam sites, moving from project toproject or staying on as dam employees.

PICTURE: CORDEAUX DAM OPENING LUNCH WITH ALDERMEN, 1927

The Upper Nepean System supplies raw bulk water to four water filtration plantsadministered by Sydney Water, via 64kilometres of tunnels, canals and aqueductscollectively known as the Upper Canal.

Water released from Cataract Dam flows down the Cataract River to Broughtons PassWeir. Water released from Nepean Dam andCordeaux Dam flows downstream to PheasantsNest Weir on the Nepean River, where it isdiverted via a seven kilometre long tunnel toBroughtons Pass Weir.

From Broughton’s Pass Weir water is diverted into the Upper Canal where it flows 57 kilometres entirely by gravity to Prospectwater filtration plant at Prospect Reservoirnear Blacktown. Prospect water filtration plant receives raw water from both the UpperNepean System and from Warragamba Damand supplies filtered water to the metropolitanregions of Sydney.

Water is also pumped from Broughtons Pass Weir to the Macarthur water filtrationplant near Appin, which serves Sydney’s rapidly expanding south–west area aroundCampbelltown, Camden, Appin, Ingleburn and Wilton.

Water in Avon Dam is reserved for the Illawarraregion and is gravity fed via pipeline to theIllawarra water filtration plant at KemblaGrange. Prior to filtering, the water is used to generate approximately 5.85 megawatts of hydro–electric power – which not only runsthe plant but any excess is fed back into thepower supply grid. Filtered water is supplied to the south coast area, from Scarborough to Gerringong.

Avon Dam can be supplied with additionalwater from Nepean Dam via a two kilometrelong interconnecting tunnel. In times of droughtNepean Dam can receive water from theShoalhaven Scheme via WingecarribeeReservoir and the Glenquarry Cut.

Water from Nepean Dam is also pumped toSydney Water’s Nepean water filtration plant,which serves people living in the areas ofPicton, Bargo, The Oaks and Oakdale.

How the Upper Nepean water supply system works

Ensuring dam safety

It is essential that all SCA dams meet therequirements of the NSW Dams SafetyCommittee (DSC) under the NSW Dams SafetyAct (1978). The DSC, the State’s regulator fordam safety, develops and implements policiesand procedures for effective dam safetymanagement in order to protect life, propertyand the environment from dam failures.

To ensure compliance with its operatinglicence, the SCA has adopted a structuredprogram of surveillance and monitoring thatcomplies with the requirements of the DSC and national and international best practice.

> DEEPENED NEPEANDAM SPILLWAY

The SCA conducts extensive routine water quality and quantity monitoring in the catchments, storages and in–flows towater filtration plants. Monitoring providesinformation to enable the best quality water to be drawn–off into the supply system, and toidentify areas requiring special catchmentmanagement attention. The SCA also conductsregular testing at several locations for thepresence of the protozoan parasites Giardiaand Cryptosporidium in the water. Informationcollected from the SCA’s monitoring programs is used for public health reportingand assessment.

MAINTAINING GOOD WATER QUALITY IN THE CATCHMENT

The SCA works with government, industry andthe community to promote good water qualityand healthy, sustainable catchments.

Extensive research is carried out by the SCAto help understand the catchment environment.The SCA also plays an important role inensuring that proposed land use anddevelopment is compatible with preservingwater quality.

Field staff undertake a range of on–groundactivities in the catchments, such as pestcontrol, fire control, erosion control and repair,regulating access, containing spills, chemicalcollections and weed control. In the SpecialAreas (land closest to the storages) theseactivities are jointly managed by the NationalParks and Wildlife Service and the SCA.

Many successful projects are also undertakenjointly with landholders and community groupsincluding riverbank stabilisation, willowremoval, revegetation and riverbank fencing.

Monitoring water quality

ENVIRONMENTAL FLOWS

The SCA recognises that the dams and weirs inthe Upper Nepean system can affect the naturalflow of water downstream. Providing water tothese stretches of river through environmentalflows is one way the SCA can help restoreecological processes and biodiversity of waterdependent ecosystems.

Water is released from the Upper Nepean damsand weirs for environmental purposes, includinga minimum daily release of 4.4 million litresfrom Nepean Dam, 1.9 million litres fromCordeaux Dam, and 1.3 million litres fromCataract Dam. A minimum of 10.5 million litresis released daily from Pheasants Nest Weir and1.7 million litres from Broughtons Pass Weir.

> AVON DAM DISCHARGE CHUTE

Did you know?

AFTER CATARACT DAM WAS BUILT, theengineers realised that a curved dam wall was stronger than a straight wall in holdingback a large volume of water. That is why allfuture dams in the Upper Nepean system were built this way.

TORPEDO NETS were placed at Cataract andCordeaux dams at the beginning of WWII toprotect Sydney’s water supply from beingdestroyed by enemy attack.

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In one of Sydney’s GREAT ENGINEERING FEATSof the 19th century, a seven kilometre longtunnel was built to connect the waters of theAvon, Cordeaux and Nepean rivers to CataractRiver. The tunnel starts at Pheasants Nest, runsunderneath the town of Wilton and empties intoCataract River at Broughtons Pass.

The discovery of KING TUTANKHAMEN’S TOMBin 1923 led to worldwide fascination with allthings Egyptian, and influenced the design ofthe gateways and valve houses of bothCordeaux and Avon dams. However, theDepression and the rise of Art Deco saw a more austere design for Nepean Dam.

< CURVED WALL OF CORDEAUX DAM

< CORDEAUX DAMGATEWAY

Recreation at the dams

All the dams in the Upper Nepean system arewithin easy driving distance from Sydney andoffer an ideal location for picnicking,barbecues, walking and sightseeing.

Facilities are set in natural bushlandsurroundings with picnic shelters, shade trees, barbecues, drinking water, gardens,viewing areas and children’s playgrounds.

Visiting hours are 10am to 5pm daily (7pm on weekends and public holidays during Daylight Saving Time).

For educational excursions and project material, please contact our Education Office on (02) 4720 0344/3

There are no entry fees to any of our dams. Picnic areas cannot be reserved.

AVON & NEPEAN DAMFACILITIES

ELECTRIC BBQS

PLAYGROUND

TOILETS

DRINKING WATER

VIEWING AREA

PICNIC SHELTERS

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CATARACT & CORDEAUX DAMFACILITIES

ELECTRIC BBQS

PLAYGROUND

TOILETS

DRINKING WATER

VIEWING AREA

PICNIC SHELTERS

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Cataract Dam is located about 84 kilometres drivesouth–west of Sydney, off theAppin–Bulli Road.

From Sydney, take the Hume Highway (F5) to the Campbelltown exit and follow the Appin Road south. At Appin, take the roadtowards Bulli–Wollongong, and then right toCataract Dam where signposted.

How to get there

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Cordeaux Dam is located about 94 kilometres drive from Sydney.

From Sydney, take the Hume Highway (F5)towards Canberra. Past Campbelltown, takethe Wollongong/Picton turnoff. The CordeauxDam entrance is about ten minutes on theright, and is signposted.

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Avon and Nepean dams aresituated approximately 100kilometres drive from Sydney.

Follow the Hume Highway (F5) south fromSydney, and take the Bargo exit to Avon andNepean dams.

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About 890 square kilometres of the UpperNepean catchment is classified as SpecialArea. In total, Special Areas cover about 3,700square kilometres of land surrounding SCAwater storages.

The Special Areas protect our water supplybecause they act as a buffer zone, helping to stop nutrients and other substances thatcould affect the quality of water entering the storages.

The Sydney Catchment Authority andthe National Parks and Wildlife Service(NPWS) jointly manage the Special Areas, inaccordance with the Special Areas StrategicPlan of Management.

This long–term plan aims to provide highquality water in the storages, ensure ecosystemintegrity, and improve the environmental qualityof the catchment areas.

Why Special Areas are protected

> UPPER NEPEANSPECIAL AREA

Public access to parts of the Special Areas isrestricted to protect water quality. This benefitsthe community by:• ensuring we have safe, clean water• protecting large areas of bushland

and plant and animal habitats• protecting threatened plants

and animal species• preserving evidence of Aboriginal occupation

dating back many thousands of years, and• preserving evidence of European exploration,

early settlement, and phases of developmentsuch as forestry, mining and dam building.

Restrictions and controls are placed on landuse, development and access within SpecialAreas. Activities such as swimming, fishing,boating and camping are prohibited, unlessotherwise specified.

How you can help keep our catchments healthy

SAVING WATER

Water is a precious resource. Each of us hasa responsibility to reduce the amount of waterwe use – no matter where we live.

By reducing the amount of water we all use, wereduce the need to build expensive new watersupply infrastructure such as dams, reservoirsand pipelines.

Reducing the amount of water we all use canalso help make more water available forenvironmental flows, which protect the healthof the rivers downstream of the dams.

The need to manage demand for water isreflected in the Operating Licences of boththe SCA and Sydney Water. The SCA is workingwith Sydney Water to encourage water savingactions around the home, garden and office.

The SCA also recognises the need to adoptexemplary practices in managing our ownbusiness. Minimising leaks in pipelines andfitting water saving appliances and devicesare just some of the ways the SCA is reducingthe amount of water we use.

WATER SAVING TIPS

For great water saving ideas, visit theSydney Catchment Authority websitewww.sca.nsw.gov.au. Follow the links to sitessuch as www.sydneywater.com.au for moreinformation. If you don’t have access to theinternet, contact Sydney Water on 13 20 92.

IN THE CATCHMENTS

People living and working in the catchmentareas play a special role in keeping ourcatchments healthy. Some of the ways peoplein the catchments help include: • using chemicals efficiently and carefully • controlling weeds and pests• retaining and planting vegetation to

prevent soil loss • protecting stream bank vegetation to

provide a buffer against pollution• managing on–site sewage systems effectively• encouraging and developing improved sewage

and stormwater management systems• preventing bushfires• reporting spills, and• getting involved in a Landcare, Streamwatch

or other local community group.

USING LESS WATER HELPS KEEP OUR CATCHMENTS HEALTHY

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STUDENTS PARTICIPATING IN STREAMWATCH TESTING

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UPPER N

EPEAN

SYSTEM

DAMS OF GREATER SYDNEY AND SURROUNDS

Upper Nepean

CONTACTING THE SYDNEY CATCHMENT AUTHORITY

SCA Head O�ce, PenrithSydney Catchment Authority:Level 2, 311 High Street, Penrith 2750PO Box 323, Penrith, NSW 2751 Phone: (02) 4725 2100 Fax: (02) 4732 3666

Website: www.sca.nsw.gov.auEmail: info@sca.nsw.gov.au

VISITOR INFORMATION

Warragamba Dam Visitors CentrePhone: (02) 4720 0349Hours: 10am to 4pm daily, except Christmas Day and Good Friday

Other SCA dams Phone (02) 4640 1200Hours: 9am to 5pm Monday to Friday

EMERGENCY REPORTING (24 HOURS)

Fires, chemical spills Freecall: 1800 061 069

FIELD OFFICE LOCATIONS

Goulburn O�cePhone: (02) 4823 4200Fax: (02) 4822 9422Hours: 8.30am to 5.00pm Monday to Friday

DepotsCordeaux DamWarragamba DamCampbelltownBlue MountainsBurrawang

PRINTED ON RECYCLED PAPERISBN 1 876951 12 5MARCH 2007

IMPORTANTInformation contained in this brochure may changeafter the date of printing. The SCA accepts noresponsibility or liability for any loss or inconvenienceincurred as a result of reliance upon informationprinted in this brochure. For the most up–to–dateinformation on SCA dams and recreational facilities,contact the SCA’s head office on (02) 4725 2100 or visitour website at www.sca.nsw.gov.au

ACKNOWLEDGEMENTThe SCA acknowledges the assistance of the Sydney Water Corporation and Sydney CatchmentAuthority Historical Research and Archives Facility in researching and supplying historical images for use in this publication.SCA076