Sydney
Supporting information
Introduction
The following set of notes provides consolidated reports for each of the water stores and systems within the Sydney region during the 2013–14 year. The water stores and systems included in the region are shown in Figure 1.
For a more detailed description of the region, please refer to the General description section of the 'Contextual information'.
Figure 1 Water stores and systems within the Sydney region
Information on all water flows to and from each water store and system are presented in this note, including between-store flows and transfers that are not presented in the water accounting statements. The between-store flows and transfers that occur in the region are presented in Figure 2.
Figure 2 Between-store flows that occur within the Sydney region
The between-store flows and transfers (Figure 2), which are eliminated from the region's water accounting statements, are shown in italics throughout the following set of notes. The allocation announcement, forfeiture and allocation remaining line items associated with each between-store abstraction (brown arrows in Figure 2) are also shown in italics in the following notes.
Surface water store
Surface water assets
The volume of surface water assets includes water held in storages (2,386,167 ML), unregulated rivers (1,903 ML) and inter-region claim on water (2,367 ML). The volume of water in regulated rivers, lakes and wetlands could not be quantified due to a lack of available data. However, the volume of water held in channels and lakes is considered to be relatively small compared to the volume held in storages.
The location of each storage within the Sydney region, total storage capacity (including dead storage) and the storage as a percentage of total storage capacity at the end of the 2013–14 year are shown in Figure 3.
Figure 3 Percentage-full volume for each storage in Sydney region on 30 June 2014
The overall storage volume within the Sydney region decreased during the 2013–14 year from 98% to 83% capacity. The volume in most storages decreased during the year. Five storages (Bundanoon, Danjera, Farmers Creek No. 2, Medway and Tallowa) were at capacity on both 30 June 2013 and 30 June 2014.
The largest storage in the region is Lake Burragorang (Warragamba Dam). Its capacity of 2,031,000 ML represents approximately 70% of the Sydney region's total storage capacity (2,862,622 ML). On 30 June 2014, Lake Burragorang was at more than 84% capacity and all other large storages including Avon, Tallowa, Cordeaux, Cateract, Woronora and Nepean were at more than 60% capacity.
Catchment runoff was the main contributor for the storage volumes. During the 2013–14 year, 1,005,920 ML of surface water runoff reached the storages within the region. This volume is approximately 51% of the total runoff that reached rivers and storages. The runoff volume to the storages was 54% less than that observed for the 2012–13 year.
Total volume of water within each storage at 30 June 2014, and at the end of the previous three years (30 June 2011, 2012, and 2013) is given in Figure 4.
The overall decrease in storage during the 2013–14 year can be attributed to decreased runoff due to the lower rainfall experienced across the region compared to the 2012–13 year (see Climate overview).
For unregulated river reaches, where data were available, static volume of water stored was estimated (1,903 ML). These reaches were Capertee River (Glen Davis to upper Colo), Coxs River (Lithgow–Kelpie Point), Shoalhaven River (Kadoona–Fossickers Flat) and Wollondilly River (Jooriland–Golden Valley).
The inter-region claim on water (2,367 ML) represents the carryover associated with the Fish River Water Supply Scheme for Sydney Catchment Authority and Delta Electricity (during the year, the holder of the licence changed from Delta Electricty to Energy Australia) for the 2013–14 year. Each agency has an annual maximum allocation entitlement from the Fish River Water Supply Scheme to supply water to their storages. The maximum carryover volume is 20% of the total allocation entitlement (Sydney Catchment Authority: 3,650 ML and Delta Electricity: 8,184 ML) into the following year.
Surface water liabilities
Surface water liabilities in the Sydney region refer to the volume of surface water allocation remaining on licence entitlements at the end of the 2013–14 year for:
- individual users (0 ML)
- urban water system (0 ML).
The water supply licences for the region have a water management year that ends on 30 June. The unused component of the annual allocation for these licence entitlements is forfeited at the end of the year; therefore, the allocation remaining is zero (tables 1 and 2).
| Account: individual users | Volume (ML) |
| Opening balance at 1 July 2013 | 0 |
| Surface water allocation announcements | 159,462 |
| Entitled diversion of allocated surface water to individual users | (42,977) |
| Adjustment and forfeiture of surface water allocation | (116,485) |
| Closing balance at 30 June 2014 | 0 |
| Account: urban water system | Volume (ML) |
| Opening balance at 1 July 2013 | 0 |
| Surface water allocation announcements | 1,040,588 |
| Entitled diversion of allocated surface water to urban water system | (557,031) |
| Adjustment and forfeiture of surface water allocation | (483,557) |
| Closing balance at 30 June 2014 | 0 |
Surface water inflows and outflows
A schematic diagram representing all the inflows and outflows associated with the surface water store in the Sydney region is provided in Figure 5.
Figure 5 Water inflows and outflows for the surface water store within the Sydney region during the 2013-14 year
Surface water inflows
The largest natural water inflow was runoff to surface water (1,986,928 ML) during the 2013–14 year. This volume reflects the below average rainfall experienced across the region (see Climate overview) and is approximately 60% less than that of 2012–13 year. It includes 1,005,920 ML that reached surface water storages (see Surface water assets).
The other natural surface water inflow is precipitation on surface water (91,668 ML). The volume of precipitation represents rainfall that fell on the major storages and river reaches within the region. The other notable natural surface water inflow, the groundwater discharge to surface water, could not be quantified due to lack of data.
The total diversion during the year under inter-region agreements was 7,499 ML. It is the volume of water received under inter-basin claim on the Fish River Water Supply Scheme by Sydney Catchment Authority and Delta Electricity.
The remaining two transfers of water to the surface water store during the 2013–14 year were discharge from the urban water system (59,678 ML) and direct discharge by users (2,485 ML). Discharge from the urban water system comprised of:
- the treated wastewater discharged into rivers (44,688 ML).
- recycled water discharged as environmental flows (14,990 ML).
Direct discharge by users represents water discharge from Wallerawang Power Station to the Coxs River upstream of Lake Lyell (2,485 ML).
Surface water outflows
The largest natural water outflow is the river outflow from the region (1,724,770 ML), which refers to the annual volume of flow to the sea during the 2013–14 year. The flow volume to the sea comprises of natural runoff leading to sea, rule-based environmental flow releases, other unspecified releases and spills from most downstream storages and weirs to rivers and treated water releases from wastewater treatment plants. This volume is about 41% of that of the 2012–13 year, reflecting that there was less water available in these rivers in 2013–14 year compared with that of 2012–13 year (see Water overview).
Evaporation from surface water during the 2013–14 year was 168,947 ML, which represents evaporation from the major storages and river sections within the region. Total evaporation during the 2013–14 year is about 19% higher than that of 2012–13 year, which may be attributed to the higher temperature and decreased rainfall (and hence less cloud cover) that occurred during the 2013–14 year (see Climate overview).
Water diversions from the surface water store, both allocated and non-allocated, are described in Surface water diversions below. The volume of surface water leakage to landscape and groundwater could not be quantified accurately due to a lack of available data.
Surface water diversions - other statutory rights
The Water Sharing Plan for Greater Metropolitan Unregulated River Water Sources and Water Sharing Plan for the Kangaroo River Water Source provide information on other statutory rights. These are the right to extract water to meet basic requirements for household purposes, watering of stock and cultural basic rights. The annual abstraction for domestic, stock and cultural purposes is assumed to be 32,530 ML, the combined total volume allocated in these two water sharing plans.
Surface water allocation diversions
Surface water allocation diversions within the Sydney region represent:
- water diversion from surface water for urban water supply system by Sydney Catchment Authority and other urban entitlement holders
- entitled diversion of allocated surface water for individual users.
Sydney Catchment Authority, the region's sole bulk water supplier, diverts surface water to water utilities within the region. In addition, several water utilities divert surface water under their local water utility entitlements. During the 2013–14 year, 557,031 ML of surface water was diverted to Sydney's urban water supply system (Figure 6), which accounts for approximately 93% of the total allocation diversion of 600,008 ML.
Figure 6 Surface water allocations and diversions for the urban water system during the 2013–14 year
The volume diverted to the urban water system includes:
- water diverted by Sydney Catchment Authority to supply water to urban holders: Sydney Water Corporation, Shoalhaven City Council, Wingecarribee Shire Council and Goulburn Mulwaree Council, raw and unfiltered water supplied by Sydney Catchment Authority to retail customers
- water diverted by other urban entitlement holders: Goulburn Mulwaree Council, Lithgow City Council and Wingecarribee Shire Council.
Figure 7 shows the surface water diverted by Sydney Catchment Authority and other urban water holders to water utilities for the urban water system during the 2013–14 year.
Figure 7 Surface water diverted to water utilities for the urban water system by Sydney Catchment Authority and other urban water holders during the 2013–14 year
The entitled diversion of allocated surface water for individual users during the 2013–14 year was 42,977 ML, which accounts for approximately 7% of the total allocation diversion (600,008 ML). The diversions from Cox River (16,889 ML) were for power generation at Mt Piper and Wallerawang power stations. The remaining volume, 334 ML to individual holders (stock and domestic) and 25,754 ML to other lumped holders, was diverted from the Hawkesbury and lower Nepean rivers.
The Water access and use note provides more information on water entitlements related to surface water allocation diversions.
Surface water forfeitures
The portion of surface water allocation that has not been abstracted at the end of the water year is either forfeited or is carried over into the next water year. According to the Water Sharing Plan for the Greater Metropolitan Unregulated River Water Sources(NSW Office of Water 2011f), carryover of any unused allocation at the end of the year is allowed. The maximum volume of carry-over allowed is determined by the rules in the water sharing plan and the volume of water diverted under the licence. However, due to limited data availability, the carryover volume could not be quantified. Therefore, for the purposes of the National Water Account 2014, it is assumed the entire unused portion of the allocation is forfeited.
Water forfeitures in the Sydney region during the 2013–14 year relate to licence entitlements for:
- individual users (116,485 ML)
- urban water system (483,557 ML).
Surface water allocation announcements
Surface water allocation announcements in the Sydney region during the 2013–14 year refer to surface water supply to:
- individual users (159,462 ML)
- urban water system (1,040,588 ML).
The surface water allocation for individual users is based on information available in the Water Sharing Plan for the Greater Metropolitan Unregulated River Water Sources. For the purposes of the National Water Account, allocation volumes are assumed to be 100% of the entitlement outlined in the water sharing plan. For major utilities (power generation; Delta Electricity and Eraring Energy) the value is based on the entitlements stated in each organisation's water management licence with an assumed allocation of 100% at the beginning of the 2013–14 year.
The water supply licences for individual users are divided into access licence categories. Figure 8 shows the annual allocation announcement for each licence category for the 2013–14 year.
The surface water allocation announcements for the urban water system (1,040,588 ML) relate to licences to divert water from storages and rivers to the Sydney region's urban water supply system as shown in Figure 6 above.
Allocated volume for Sydney Catchment Authority is 987,000 ML under the 'major utility (urban water)' water access licence category. It comprises of the diversions to:
- Goulburn Mulwaree Council
- Sydney Water Corporation
- Shoalhaven City Council
- Wingecarribee Shire Council
- retail customers.
In addition, under the 'major utility (urban water)' licence category, Sydney Water Corporation is allocated a volume of 20,075 ML to divert from the Hawkesbury and lower Nepean rivers. Local water ulilities include Goulburn Mulwaree Council, Lithgow City Council, Shoalhaven City Council, Wingecarribee Shire Council and Palerang City Council.
A more detailed description of surface water allocations and associated water rights in the Sydney region is given in the Surface water rights note.
Surface water balancing item
The balancing item volume represents the difference between the measured opening and closing balances of the surface water store, after physical inflows and outflows have been applied (Table 3). This item is an indication of both the accuracy of the volumes reported and the degree to which the reported water flows represents a complete surface water store balance.
| Account: surface water store | Volume (ML) |
| Opening balance (at 1 July 2013) | 2,838,384 |
| Total surface water inflows | 2,148,258 |
| Total surface water outflows | (2,526,255) |
| Closing balance (at 30 June 2014) | (2,388,070) |
| Balancing item | 72,317 |
The calculation of the water balance on the surface water store yielded a balancing item of 72,317 ML. This is approximately 3% of the total surface water store volume at the end of the 2013–14 year and less than 4% of the total surface water inflows during the 2013–14 year.
It is likely that the balancing item is primarily attributed to uncertainties associated with the runoff (a large source of surface water increase). The Bureau derived runoff volumes from a rainfall–runoff model and Sydney Catchment Authority used water balance calculations. It is reasonable to expect a 10–20% uncertainty around the estimated runoff volume (+/– 90,000 ML).
The balancing item is also attributed to the fact that river and floodplain losses cannot be quantified in the account. It is likely that these losses are a relatively large source of surface water decrease throughout the region.
Groundwater store
The groundwater store is not discussed for the Sydney region as volumes related to groundwater store could not be quantified in a way that is complete, neutral and free from material error. Also, it is not recognised in the water accounting statements as its contribution is very minimal.
Urban water system
Urban water assets
The Sydney region’s urban water system comprises four subcomponents:
- urban water supply system (– ML)
- wastewater system (– ML)
- recycled water system (– ML)
- urban inter-region claim on water (356 ML).
The volumes of water within the urban water supply system, wastewater system and the recycled water system cannot be quantified due to a lack of available data and are not considered material to the Account.
Urban water claims
The urban claim on surface water (0 ML) is equivalent to the volume of surface water allocation remaining for urban water supply licence entitlements at the end of the 2013–14 year. Details of allocation remaining for the urban water supply system are provided in Table 4. There are no groundwater licence entitlements for the urban water system.
| Account: urban claim on surface water | Volume (ML) |
| Opening balance at 1 July 2013 | 0 |
| Increase of urban claim on surface water | 1,040,588 |
| Entitled extraction of allocated surface water to urban water system | (557,031) |
| Adjustment and forfeiture of urban claim on surface water | (483,557) |
| Closing balance at 30 June 2014 | 0 |
The urban claims throughout the Sydney region do not allow unused water to be carried over at the end of the year, any unused water is forfeited, resulting in zero carryover volume.
Urban water system inflows and outflows
A schematic diagram representing all the inflows and outflows associated with the urban water system in the Sydney region is provided in Figure 9.
Figure 9 Water inflows and outflows for the urban water system within the Sydney region during the 2013–14 year
Urban water supply system inflows
There are four sources of water for the urban water supply system:
- allocated surface water (557,031 ML)
- allocated groundwater (0 ML)
- desalinated water (0 ML)
- inter-region import (789 ML).
Figure 10 compares volumes received from different sources for the most recent four years.
Figure 10 Water sources used in Sydney's urban water system and total volume for the years ending 30 June 2011, 2012, 2013 and 2014
The total volume of surface water diverted to the urban water system during the 2013–14 year (557,820 ML) is a marginal increase from the previous year (543,311 ML).
Entitled diversion of allocated surface water to the urban water supply system (557,031 ML) is the Sydney region’s primary source of water for urban water supply (Figure 10); it made up more than 99% of the inflows to the system during the 2013–14 year.
Delivery of water from outside the region (789 ML) contributed less than 1% of urban water supply, which is similar to the figures for the previous few years. This delivery refers to surface water diversion from Fish River Water Supply Scheme by Lithgow City Council.
Desalinated water was not provided to the Sydney region's urban water supply system during the 2013–14 year.
Wastewater and recycled water system inflows
Total wastewater collected during the 2013–14 year was 480,243 ML, a 5% decrease from the previous year. Shoalhaven City Council produces recycled water at sewerage treatment plants outside the region boundary and imports to the region. The volume of wastewater collected by each water authority is given in Figure 11.
Figure 11 Wastewater inflows and outflows in Sydney region during the 2013–14 year
The volume shown for Shoalhaven City Council 5,297 ML includes the recycled water imported into the region (1,580 ML) during the 2013–14 year.
Urban water supply system outflows
The major outflows from the water supply system during the 2013–14 year were:
- delivery to urban water users for residential, commercial, industrial, municipal and other uses (487,104 ML)
- transfer of potable water outside of the region by Shoalhaven City Council (4,258 ML)
- losses from the urban water supply system (55,543 ML).
The largest water outflow from Sydney's urban water supply system was the delivery to urban water users from the water supply system (487,104 ML) of which 483,030 ML was potable water and 4,047ML was nonpotable water.
The losses from the urban water supply system, 55,543 ML, for the 2013–14 year was less than the volume reported for the 2012–13 year (60,585 ML). The 2013–14 year volume was comprised of leakage to groundwater from non-revenue water—pipe leakage (40,390 ML) and other non-revenue water losses (15,153 ML).
Wastewater and recycled water system outflows
The major outflows from the wastewater and recycled water systems during the 2013–14 year were:
- treated wastewater discharged to sea (394,499 ML)
- treated wastewater discharged to surface water (44,688 ML)
- recycled water delivered to the environment (14,990 ML)
- recycled water delivered to urban users and onsite use (22,018 ML)
- evaporation from wastewater treatment plant lagoons (253 ML)
- other losses (3,756 ML).
Recirculation of treated wastewater and recycled water occurs in the system and may be subjected to additional treatment and/or re-use on site. The reported outflows exclude any such recirculated volumes in the system.
Figure 12 Wastewater outflows from Sydney's wastewater system during the 2013–14 year
The largest outflow from the wastewater system is wastewater discharge outside of region which is wastewater treated and discharged into the sea.
Decrease of urban water claims
The portion of the urban water claim that has not been abstracted at the end of the water year is forfeited, that is, there is no carry-over of entitlements into the next water year. The adjustment and forfeiture of the urban claim on surface water in the Sydney region during the 2013–14 year was 483,557 ML.
Increase of urban water claims
Increase of water claims for the urban water system refers to allocation announcements for water abstraction made during the year. The increase of urban claim on surface water in the Sydney region during the 2013–14 year was 1,040,588 ML.
Urban water system balancing item
The balancing item volume represents the difference between the measured opening and closing balances of the urban water system, after physical inflows and outflows have been applied (Table 5). This item is an indication of both the accuracy of the volumes reported and the degree to which the reported water flows represents a complete urban water system store balance.
| Account: urban water system> | Volume (ML) |
| Opening balance at 1 July 2013 | 0 |
| Total urban water system inflows | 1,039,643 |
| Total urban water system outflows | (1,027,109) |
| Closing balance at 30 June 2014 | 0 |
| Balancing item | 12,534 |
The calculation of the water balance on the urban water system yielded a balancing item is 12,534 ML. This is less than 2% of of the total urban water system inflows during the 2013–14 year.
Unaccounted-for difference
The volume recognised in the water accounting statements (84,998 ML) represents the total unaccounted-for difference for the Sydney region for the 2013–14 year.
The unaccounted-for difference is the volume necessary to reconcile the opening water storage and closing water storage with the total water inflows and total water outflows reported in the water accounting statements (Table 6).
| Account: water storage | Volume (ML) |
| Opening balance at 1 July 2013 | 2,838,384 |
| Total water inflows | 2,571,192 |
| Total water outflows | (2,936,655) |
| Closing balance at 30 June 2014 | (2,388,070) |
| Unaccounted-for difference | 84,851 |
The unaccounted–for difference can also be calculated by summing the volumes necessary to reconcile (balance) the opening and closing storage with the water inflows and outflows of each of the separate water stores of the region, as shown in Table 7.
| Balancing item | Volume (ML) |
| Surface water store | 72,317 |
| Groundwater store | – |
| Urban water system | 12,534 |
| Unaccounted-for difference | 84,851 |
Table 7 shows that the unaccounted-for difference volume is primarily explained by the balancing item of the surface water store. The surface water balancing item is largely attributed to uncertainty associated with runoff to surface water (see Surface water note).