Physical information

General description

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

Population: 4.71 million (Australian Bureau of Statistics [ABS] 2013)

The Sydney region is located on the central coast of New South Wales. It includes Sydney, Australia's most populous city, and is home to 63% of New South Wale's total population. The region spreads from Nowra in the south to Broken Bay in the north; from Lithgow and Goulburn to the west; and to the Pacific Ocean on the east coast, as shown in figures P1 and P2.

Figure P1 Location map of Sydney region within Australia
Figure P1 Location map of 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 catchment.

The Sydney region excludes the north-eastern subcatchments of the Hawkesbury–Nepean catchment starting from Mangrove Creek. These subcatchments were excluded in the Water Sharing Plan for the Greater Metropolitan Region Unregulated River Water Sources (New South Wales) and make little contribution to the region's 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 is primarily rural areas and national parks, while the downstream reach contains small urban areas surrounded by rural areas.

Hawkesbury–Nepean River catchment

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

At the top of the catchment, the Wollondilly River joins with the Coxs River at Lake Burragorang and flows as the Warragamba River until the Nepean River confluence. From this point, the Nepean River flows through until its confluence with Gross River, after which it is named the Hawkesbury River. The main tributaries of the Hawkesbury–Nepean River commence in rural areas and national parks. The Hawkesbury River becomes 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. Most of the 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

The Sydney region is physically defined above (see Figure P2),  and the National Water Account 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


Urban centre population









Source: ABS (2013)

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 uses within the Sydney region are shown in Table P2 (ABRS 2010). Figure P3 shows the distribution of these land uses.

Table P2  Major land uses within the Sydney region

Land use activity

Area (km2)

Area (% of total)

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, an estuarine systems and a designated Ramsar 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 Unregulated River Water Sources (New South Wales) 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 Unregulated River Water Sources (New South Wales) 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.

Figure P4 shows the significant aquatic ecosystems of the Sydney region.

Figure P4 Map showing the significant aquatic ecosystems of the Sydney region
Figure P4 Map showing the significant aquatic ecosystems of the Sydney region

Significant indigenous cultural places and practices

The Kangaroo River is an important area for the Nowra and Illawarra Local Aboriginal Land Councils. The Kangaroo River has been recognised as an area of cultural significance as well as a source of food for Aboriginal communities. The Water Sharing Plan for the Kangaroo River Water Source provides for native title rights as basic landholder rights.

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 the Kurnell Desalination Plant to the 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 together with their managing authority. Opening and closing storage volumes for the 2012–13 year are available in line item 1.1 Storages.

Table P3  Storages in the Sydney region
Managing authority
Storage Total capacity (ML) Dead storage volume (ML)
Delta Electricity
Lake Lyell



Lake Wallace



Thomsons Creek






Goulburn Mulwaree Council









Lithgow City Council Farmers Creek No. 2


Shoalhaven City Council Bamarang






Flat Rock Creek






Sydney Catchment Authority Avon



Blue Mountains3









Fitzroy Falls



Lake Burragorang (Warragamba)



Lake Yarrunga (Tallowa)


















Wingecarribee Shire Council Bundanoon







Total 2,862,622 108,471
1–2  Total storage capacity is the sum of the accessible and dead storage capacities.
3  Blue Mountains storages include Medlow, Greaves Creek, Upper Cascade, Middle Cascade, and Lower Cascade reservoirs.

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

A map of the storages within the Sydney region is provided in Figure P5.

Figure P5 Map showing the storages of the Sydney region
Figure P5 Map showing the storages of the Sydney region

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

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 and Illawarra.

Figure P6 shows the mean monthly flows and mean monthly rainfall experienced in the Colo River within the Hawkesbury–Nepean catchment, and for the Shoalhaven River. Figure P7 shows the location of these stations along these main rivers. 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 P6  Graph of mean monthly flows along the Colo and Shoalhaven rivers and mean monthly rainfall for the Sydney region
Figure P6  Graph of mean monthly flows along the Colo and Shoalhaven rivers and mean monthly rainfall for the Sydney region

Figure P7  Map of streamflow gauging stations along the main rivers within the Sydney region
Figure P7  Map of streamflow gauging stations along the main rivers within the Sydney region

Intervalley transfers

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.

Further, there are intervalley 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.


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 (New South Wales) 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 P8 shows a map of the groundwater management units in the Sydney region.

Figure P8 Map of groundwater management units within the Sydney region
Figure P8 Map of groundwater management units within the Sydney region

Desalinated water

Sydney's desalination plant at Kurnell commenced delivering water on 28 January 2010 (Sydney Water Corporation 2012). 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.

Other water resources and systems

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 14 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 nine 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 Fish River Customer Council. The members of this council 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.