Physical information

General description

Area: 30,800 km2 (Australian Bureau of Rural Science 2010)

Population: 4.65 million (Australian Bureau of Statistics 2012)

The Sydney region is located on the central coast of New South Wales. It is the most populous metropolitan area in Australia and is home to 63% of the total State population. It spreads from Shoalhaven Heads in the south to Broken Bay in the north and from Lithgow and Goulburn to the west to the Pacific Ocean on the east coast as shown in Figures P1 and P2.

Figure P1  Location map of the Sydney region within Australia
Figure P1  Location map of the Sydney region within Australia

Figure P2  Contextual map of the Sydney region
Figure P2  Contextual map of the Sydney region

The Sydney region includes:

  • Shoalhaven River catchment
  • Hawkesbury–Nepean River catchment
  • Illawarra and metropolitan Sydney rivers.

The Sydney region excludes the eastern subcatchments of the Hawkesbury–Nepean catchment starting from Mangrove Creek. These subcatchments were excluded in the NSW Water Sharing Plan for the Greater Metropolitan Region Unregulated River Water Sources and make little contribution to the Sydney region water sources.

Shoalhaven River catchment

Catchment area: 7,300 km².
Catchment length: approximately 300 km.

The Shoalhaven River commences between the Gourock and Minuma ranges. The upstream catchment primarily contains rural areas and national parks while the downstream reach is an urban area.

Hawkesbury–Nepean River catchment

Catchment area: 22,000 km².
Catchment length: 339 km.

At the top of the catchment, the Wollondilly River confluences with the Coxs River at Lake Burragorang and flows as the Warragamba River until the Nepean River confluence. The river is named the Hawkesbury River after the confluence with the Gross River. The main tributaries of the Hawkesbury–Nepean River commence in rural areas and national parks. The river is tidal after its confluence with the Colo River.

llawarra and metropolitan Sydney rivers

The rivers of the Illawarra and metropolitan Sydney are relatively small. The main Illawarra rivers are the Minnamurra River and Macquarie Rivulet. The main metropolitan Sydney rivers are the Georges, Woronora and Hacking rivers in the south and the Parramatta River in the north.

General topography

The upstream reaches of the catchments in the Sydney region are hilly to mountainous country. The most downstream reaches are urbanised coastal areas with tidal rivers. The city of Sydney lies over the Cumberland Plain, which is a relatively flat region to the southwest of the Sydney Harbour, and the Hornsby Plateau, which is a sandstone plateau mainly to the north of the harbour. The Hornsby Plateau is dissected by steep valleys.

Description of the region

Within the geographical boundaries described above, the region includes all of the water resources within or beneath the region except for:

  • off-channel water, such as landscape catchment storages (also known as farm dams) and other off-channel storages used to harvest floodwater or collect rainwater, as it constitutes water that is already abstracted and no longer available for sharing
  • water stored in the landscape, such as soil moisture.

For more information regarding items in this water accounting report, please refer to the Water accounting policies.

Land use

Major population centres within the region

The major population centres with their respective populations for the Sydney region are shown in Table P1.


Table P1  Major population centres for the Sydney region











Source: Australian Bureau of Statistics (2012)

A number of small towns are interspersed throughout the rest of the region including Lithgow, Braidwood and Moss Vale.

Land use activities

The major land use activities in the Sydney region are shown in Table P2 (Australian Bureau of Rural Science 2010). Figure P3 shows the distribution of these land uses.

Table P2  Major land use activities in the Sydney region

Land use activity

Area (km2)

Total area of the region (%)

Conservation and natural environments



Dryland agriculture









Irrigated agriculture






Other intensive uses












Figure P3  Map of land use in the Sydney region
Figure P3  Map of land use in the Sydney region

Land use activities that are major water users in the region are as follows (New South Wales Office of Water 2011b):

  • residential supplies in urban and rural areas
  • industry
  • mining
  • power generation
  • forestry
  • dairy
  • grazing
  • cereal cropping
  • horticulture.

The agricultural land use activities mentioned above do not include irrigated agriculture. Irrigated agriculture occupies less than 1% of land use in the region, and there are no major irrigation districts.

Significant aquatic ecosystems

The Sydney region includes the Towra Point Nature Reserve, a Ramsar-listed wetland, on the southern and eastern shores of Botany Bay. There are also 25 nationally important wetlands, listed in the  Directory of Important Wetlands in Australia.

The Water Sharing Plan for the Greater Metropolitan Region identifies 29 river management zones that were assessed as having high instream values. These were identified according to a number of criteria including the presence of threatened species or ecological communities that are likely to be sensitive to water abstraction.

Several water sources are known to host endangered ecological communities in the Sydney region. The Hawkesbury–Nepean catchment contains Maroota Sands Swamp Forest and Sydney Freshwater Wetlands, both of which are highly sensitive to water abstraction (New South Wales Office of Water 2011a). Sydney Freshwater Wetlands is the name given to the plant community characterised by the assemblage of specific species restricted to freshwater swamps in swales and depressions on sand dunes and low nutrient sandplain sites in coastal areas (New South Wales Office of Environment and Heritage 2011). Sydney Freshwater Wetlands also occur in the Illawarra catchment.

The Water Sharing Plan for the Greater Metropolitan Region also identifies high priority groundwater-dependent ecosystems that include wetlands, karst systems and endangered ecological communities. There are 21 karst systems (including the major cave systems of Jenolan, Wombeyan and Bungonia) and five vegetation communities that are also considered to be groundwater dependent.

Water resources

Surface water is the main water source in the Sydney region. Surface water resources within the region were developed to meet the water needs of Sydney. Reservoir capacity in the Sydney region is one of the largest in the world per head of population (New South Wales Office of Water 2010a). This capacity is required due to the irregular interannual rainfall runoff patterns experienced in the region, and the resultant challenges this poses for a reliable water supply. The flows from a number of main rivers in the region are heavily controlled by dams and numerous major weirs.

The other water sources for the region are:

  • groundwater
  • desalinated water supply from Kurnell plant to Sydney metropolitan area
  • recycled water supply by Sydney Water Corporation (Sydney Water) and several other local councils
  • inter-basin transfers to the region from the Fish River Water Supply Scheme.

Surface water

Major storages

There is an extensive storage and weir network for capturing streamflows in many of the streams in the Sydney region. These storages provide water for urban centres, industries, power generation and many other minor uses. Table P3 shows a list of the major storages and their primary purpose. Opening and closing storage volumes for the 2012 Account are available in line item 1.1 Storages.

Table P3  Storages in the Sydney region
Storage Total storage capacity (ML)1 Dead storage volume (ML) Purpose 
Lake Lyell 34,192 2,083 Power generation for Mt Piper and Wallerawang power stations
Lake Wallace 4,004 1,798
Thomsons Creek 27,500 0
Pejar 9,000 90 Urban water supply to Goulburn Mulwaree Council area
Sooley 6,250 300
Bamarang 3,800 100 Urban water supply to the Shoalhaven City Council area
Danjera 7,660 2,300
Flat Rock Creek 400 0
Avon 214,360 67,660 Urban water supply to Sydney Metropolitan region, Wingecarribee reservoir supplies water to Goulburn Mulwaree Council via the Southern Highlands pipeline 
Blue Mountains2 2,890 0
Cataract 97,370 180
Cordeaux 93,640 0
Lake Burragorang (Warragamba Reservoir) 2,031,000 4,000
Nepean 67,730 370
Prospect 48,200 14,870
Wingecarribee 25,880 1,750
Woronora 71,790 0
Fitzroy Falls 22,920 12,970 Power generation
Lake Yarrunga (Tallowa Reservoir) 90,000 0
Bundanoon 1,170 Not available Urban water supply to Wingecarribee Shire Council area
Medway 2,046 Not available
Farmers Creek no. 2 450 Not available Urban water supply to Lithgow City Council
Total 2,862,252 108,471
  1. Total storage capacity is the sum of the accessible and dead storage capacities.
  2. Blue Mountains storages include Medlow Reservoir, Greaves Creek Reservoir, Upper Cascade Reservoir, Middle Cascade Reservoir and Lower Cascade Reservoir.

Water from the Shoalhaven catchment is able to be diverted to the Hawkesbury–Nepean catchment through Lake Yarrunga (Tallowa Dam), Bendeela Pondage and Fitzroy Falls Reservoir.

A map of the storages of the Sydney region is provided in Figure P4.

Figure P4  Map showing storages of the Sydney region
Figure P4  Map showing storages of the Sydney region


A large part of the supply network is managed by Sydney Catchment Authority, other water supplies in the area are managed by Shoalhaven City Council, Wingecarribee Shire Council and Sydney Water. More information on Sydney Catchment Authority' supply network is available from the Sydney Catchment Authourity website.

Streamflow summary

There are three main river systems within the Sydney region:

  • Hawkesbury–Nepean River catchment
  • Shoalhaven river catchment
  • Illawarra catchment which includes the metropolitan rivers of Sydney.

Figure P5 shows the mean monthly flows and mean monthly rainfall experienced in the Colo River within the Hawkesbury–Nepean catchment and the Shoalhaven River in the Shoalhaven River catchment. Figure P6 shows the location of these stations in the context of the Sydney region. Further information about monthly flows at these sites can be found in the Water overview. Information about climatic conditions in the region can be found in the Climate overview.

Figure P5  Graph of mean monthly flows in the Colo and Shoalhaven rivers and mean monthly rainfall in the Sydney region
Figure P5  Graph of mean monthly flows in the Colo and Shoalhaven rivers and mean monthly rainfall in the Sydney region

Figure P6  Map of streamflow gauging stations used to develop flow charts
Figure P6  Map of streamflow gauging stations used to develop flow charts

Inter-valley transfers

There are two inter-valley water transfer systems to and from the Sydney region:

  • import from the Fish River Water Supply Scheme
  • export to the Clyde River catchment.

Further, there are inter-valley water transfers within the Sydney region linking the Shoalhaven catchment, the Hawkesbury–Nepean catchment and the Sydney coastal catchments. These transfers are not accounted for in this water account as they occur within the region, and within the surface water store.

Import from the Fish River water supply scheme

The Fish River water supply scheme, which is located outside the Sydney region and managed by the New South Wales State Water Corporation (State Water), delivers water from Oberon Reservoir and Duckmaloi Weir to the following major customers:

  • Oberon township
  • Lithgow villages
  • Sydney Catchment Authority, Blue Mountains storages
  • Delta Electricity.
As the Oberon township is outside the Sydney region boundaries, it has not been included in the Sydney region account.
Export to the Clyde River catchment

The Shoalhaven City Council releases treated and untreated water from the Shoalhaven catchment to the Clyde River catchment, which is outside the Sydney region. Releases are made through Bamarang and Flat Rock reservoirs, respective water treatment plants and the supply network.


The groundwater resources of the Sydney region are mainly utilised for irrigation and industrial purposes. There are 13 groundwater sources identified in the Sydney region. A groundwater source as defined in the Water Sharing Plan for the Greater Metropolitan Groundwater Sources is one or more places where water naturally occurs below the surface of the ground. 

These groundwater sources are broken into three types, are as follows:

1. Fractured rock  

  • Goulburn
  • Coxs River

2. Porous rock

  • Sydney Basin South
  • Sydney Basin Richmond
  • Sydney Basin North
  • Sydney Basin Nepean
  • Sydney Basin Coxs River
  • Sydney Central Basin
  • Sydney Basin Blue Mountains

3. Coastal sands, tertiary sands and alluvial

  • Metropolitan Coastal Sands
  • Maroota Tertiary Sands
  • Botany Sandbeds
  • Hawkesbury Alluvium

The Water Sharing Plan for the Greater Metropolitan Region Groundwater Sources Background Document provides further details about these groundwater sources. For management purposes, these groundwater sources have been broken into groundwater management units. Figure P7 shows a map of the groundwater management units in the Sydney region.

Figure P7  Map of groundwater management units of the Sydney region
Figure P7  Map of groundwater management units of the Sydney region


Other water resources and systems

Desalinated water

Sydney's desalination plant at Kurnell commenced delivering water on 28 January 2010 (Sydney Water Corporation 2012a). It operates at full production capacity when the total Sydney Catchment Authority storage level is below 70%, and continues until the level returns to 80%. The plant can supply 250 ML of water a day or up to 15% of greater Sydney's current water needs. As part of the plant commissioning process, it operated continuously for two years until June 2012 to ensure it met planned performance and reliability targets. Since June 2012, the plant has been taken offline and would be brought back online within eight months of the total Sydney Catchment Authority storage system falling below 70% capacity.

Recycled wastewater

A number of water utilities in the Sydney region manage the production of recycled water from wastewater as follows:

  • Sydney Water Corporation manages 13 recycled water plants in the Blue Mountains, Illawarra and Greater Sydney areas. Recycled water is distributed for residential, commercial, industrial, agricultural and other purposes.
  • Shoalhaven City Council produces recycled water at five wastewater treatment plants for commercial, industrial, agricultural and other uses.
  • Wingecarribee Shire Council, Lithgow City Council and Goulburn Mulwaree Council produce small quantities of recycled water.
Fish River Water Supply Scheme

State Water has a deemed water management licence for the Fish River water supply scheme and operates it in collaboration with the Customer Services Committee. The members of this committee include three organisations:

  1. Sydney Catchment Authority
  2. Lithgow City Council
  3. Delta Electricity.

The Oberon Shire Council also relies on water from the Fish River Water Supply Scheme but has not been included in the Sydney account as it falls outside of the region boundaries.

More information on the scheme is available under Water rights.