South East Queensland
Water resources and systems

Introduction


The following set of notes provides consolidated reports for each of the water stores and systems within the South East Queensland (SEQ) region during the 2012–13 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.

 

Figure 1 Schematic diagram of the water stores and systems within the South East Queensland region
Figure 1 Schematic diagram of the water stores and systems within the South East Queensland region

Information on all water flows to and from each water store and system are presented in the following set of notes, 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.

The numbers on the diagram refer to the line item numbers in the water store notes. For each between-store flow, there are two line item numbers: one refers to flow out of a water store and the other refers to flow into a water store.


Figure 2  Schematic diagram of between-store flows that occur within the South East Queensland region; line item numbers are provided next to the flows
Figure 2  Schematic diagram of between-store flows that occur within the South East Queensland region; line item numbers are provided next to the flows

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


Background

A description of the South East Queensland (SEQ) region's surface water resources is provided in the Contextual information.

Water in store

The Statement of Water Assets and Water Liabilities for the surface water store (Table 1) shows that total surface water increased during the 2012–13 year in the SEQ region. 

Table 1 Statement of Water Assets and Water Liabilities for the surface water store
Water assets

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

1 Surface water    
1.1 Storages

2,554,869

2,479,671

1.2 Unregulated river

1.3 Regulated river

1.4 Lakes and wetlands

Total surface water assets

2,554,869

2,479,671

     
Water liabilities    
5 Surface water liability    
5.1 Surface water allocation remaining 12,153

12,153

Total surface water liabilities 12,153

12,153

     
Opening net water assets 2,467,518

2,206,865

Change in net water assets 75,198

260,653

Closing net water assets 2,542,716

2,467,518

The surface water storage volume includes water that was held in reservoirs, weirs, lakes, and major dams, where these data are available. For the purposes of the water accounting statements, all of these surface water storages are reported at line item 1.1 Storages as the volumes of water held in these storages are used to administer entitlements. The volume of water in rivers and natural lakes and wetlands could not be quantified in a way that is complete, neutral, and free from material error due to a lack of available data.

The location of surface water storages in the SEQ region and the volume of water including dead storage held in each of these storages (as a percentage of total storage capacity) at the end of the 2012–13 year is shown in Figure 3.


Figure 3 Location map of surface water storages within the South East Queensland region; the % full volume on 30 June 2013 for each water storage is also shown
Figure 3 Location map of surface water storages within the South East Queensland region; the % full volume on 30 June 2013 for each water storage is also shown

 

The volume of water held in all storages within the SEQ region increased by approximately 3% during 2012–13 (Table 1). At the end of the 2012–13 year storage volume, as a percentage of the total storage capacity (% full), was very high in the region, at almost 99%. The majority of surface water storages in SEQ were more than 90% full (Figure 3). The increase in overall surface water storage may be attributed to the accumulation of water received from flood at the end of January 2013. In particular, the region experienced above-average rainfall (see Climate overview). Significant increase in storage was observed for Wivenhoe dam during the 2012-13 year.

Changes in water store

The Statement of Changes in Water Assets and Water Liabilities and the Statement of Water Flows for the surface water store are provided in Table 2 and Table 3, respectively.  

Table 2 Statement of Changes in Water Assets and Water Liabilities for the surface water store
Water asset increases

2012–13
volume
(ML)

2011–12
volume
(ML)

9 Surface water increases    
9.1 Precipitation on surface water

260,396

241,032

9.4 Runoff to surface water

7,182,219

5,874,622

9.9 Discharge from urban water system

39,413 62,517
9.10 Direct discharge by user 5,274

6,964

 Total surface water increases 7,487,302

6,185,135

     
Water liability decreases    
13 Surface water liability decreases    
13.1 Adjustment and forfeiture of surface water allocation 67,318

67,399

13.2 Adjustment and forfeiture of surface water allocation – urban water system

221,763

230,474

 Total surface water liability decreases 289,081

297,873

     
Water asset decreases    
17 Surface water asset decreases    
17.1 Evaporation from surface water 279,163

245,731

17.2 River outflow from the region 7,154,690

3,631,308

17.4 Leakage to landscape 259,661 232,271
17.6 Surface water diversions– other statutory rights 3,628

3,628

17.7 Entitled diversion on non-allocated surface water to users 9,035

9,035

17.8 Entitled diversion of non-allocated surface water to urban water system

3,357

4,383

17.21 Other surface water decreases 6,508

6,165

Total surface water asset decreases 7,716,042

4,132,521

     
Water liability increases    
21 Surface water liability increases    
21.1 Surface water allocation announcements 73,304

73,304

21.2 Surface water allocation announcements – urban system

442,826

442,826

Total surface water liability increases 516,130

516,130

     
Balancing item – surface water (530,987)

1,573,704

Change in net water assets 75,198

260,653

 

Table 3. Statement of Water Flows for the surface water store
Water inflows

2012–13
volume
(ML)

2011–12
volume
(ML)

9 Surface water inflows    
9.1 Precipitation on surface water 260,396 241,032
9.4 Runoff to surface water 7,182,219 5,874,622

9.9 Discharge from urban water system

39,413 62,517
9.10 Direct discharge by user 5,274 6,964
Total surface water inflows 7,487,302

6,185,135

     
Water outflows    
17 Surface water outflows    
17.1 Evaporation from surface water 279,163 245,731
17.2 River outflow from the region 7,154,690 3,631,308
17.4 Leakage to landscape 259,661 232,271
17.6 Surface water diversions– other statutory rights 3,628 3,628
17.7 Entitled diversion on non-allocated surface water to users 9,035 9,035

17.8 Entitled diversion of non-allocated surface water to urban water system

3,357 4,383
17.11 Entitled diversion of allocated surface water to users 5,986 5,986

17.12 Entitled diversion of allocated surface water to urban water system

221,063 212,352
17.21 Other surface water decreases 6,508 6,165
Total surface water outflows 7,943,091 4,350,859
     
Balancing item – surface water (530,987) 1,573,704
     
Opening water storage 2,479,671 2,219,099
add/(less): Change in water storage 75,198 260,572
Closing water storage 2,554,869 2,479,671

Inflows to the surface water store were lower (<6%) than outflows from the surface water store during the 2012–13 year. A schematic diagram representing all the inflows and outflows associated with the surface water store in the SEQ region is provided in Figure 4. The inflow and outflow volumes for the surface water store during the 2012–13 year are given in Table 3.


Figure 4 Schematic diagram of water inflows and outflows for the surface water store within the South East Queensland region during the 2012–13 year; line item numbers are provided in brackets
Figure 4 Schematic diagram of water inflows and outflows for the surface water store within the South East Queensland region during the 2012–13 year; line item numbers are provided in brackets


 

The most significant contribution to surface water inflows was runoff to surface water that was a direct result of above-average rainfall experienced by the SEQ region during the 2012–13 year. By comparison, all other surface water inflows were minor. Decreases to the surface water store were mainly due to river outflow to sea and, combined with evaporation and leakage, far exceeded decreases to the surface water store due to diversions.

Allocation diversions

Figure 5 shows that the majority (92%) of surface water diversions in the SEQ region during 2012–13 were for urban water supply within the region (line item 17.8 Entitled diversion of non-allocated surface water to urban water system and line item 17.12 Entitled diversion of allocated surface water to urban water system). The volume of water diverted to the urban water supply system from surface water increased by 3% compared to the volume diverted in 2011–12. This can be attributed to an increased reliance on surface water due to an increase in availability of the resource and a decline in the reliance on groundwater and desalinated water resources.

In contrast, non–urban surface water diversions (line item 17.11 Entitled diversion of allocated surface water to users, 17.6 Surface water diversions – other statutory rights and 17.7 Entitled diversion of non-allocated surface water to users), which accounted for only a very small portion (8%) of surface water diversions in the region, did not change. Diversions of this nature are typically for riparian entitlement diversions, stock and domestic and irrigation purposes (see individual line items for more detail).

Figure 5 shows that water transfer from SEQ region (line item 17.21 Other surface water decreases) to Toowoomba Regional Council increased marginally (approximately 5%) in 2012–13. 

Figure 5 Diversions from surface water within the South East Queensland region during the 2012–13 year and 2011–12 comparison year; line item numbers are given in brackets
Figure 5 Diversions from surface water within the South East Queensland region during the 2012–13 year and 2011–12 comparison year; line item numbers are given in brackets

These diversions are all associated with a water access entitlement. When an allocation is announced, an obligation (water liability) is created on the surface water to deliver water to the users. Where the water year matches the 2013 Account year (July 2012–June 2013), the portion of the announced allocations that were not diverted by the end of the year was forfeited.

The entitlement, allocation announcement, and forfeiture for each of these water rights during the 2012–13 year are provided in the Water rights, entitlements, allocations and trade notes.

Balancing item

This volume represents the volume necessary to reconcile the opening and closing balances of the surface water store with the physical water inflows and outflows. The balancing item is calculated according to Table 4.

 

Table 4 Balancing item for the surface water store for the 2012–13 year

Account

Volume (ML)

Opening balance at 1 July 2012

2,479,671

Total surface water inflows (see Table 3)

7,487,302

Total surface water outflows (see Table 3)

(7,943,091)

Closing balance at 30 June 2013

(2,554,869)

Balancing item – surface water store

(530,987)

  

The calculation of the water balance on the surface water store yielded a balancing item of -530,987 ML which is approximately 7% of the total surface water inflows during the 2012-13 year. It is likely the balancing item is primarily attributed to uncertainty associated with the estimate of rainfall-runoff (a large source of surface water increase, line item 9.4 Runoff to surface water) and also outflow to outside region (a large source of surface water decrease, line item 17.2 River outflow from the region). The rainfall-runoff volume is derived from a rainfall-runoff model and it is reasonable to expect an uncertainty around the estimated runoff volume that could account for the balancing item. The surface water outflow to sea was based on flow gauge data and estimated flow from the area downstream of the gauging station.

Groundwater

Background

A description of the South East Queensland (SEQ) region's groundwater resources are provided in the Groundwater section of the 'Contextual information'.

Water in store and groundwater asset

Nominal volume (line item 33.2 Groundwater access entitlement for non-allocated extractions) of water in the benefitted area of the Lockyer Valley groundwater management area (GMA) in the Central Lockyer water supply scheme (WSS) was included as the groundwater asset in the 2012 Account. Progressive assessment of volumetric extractions in additional implementation areas of the Lockyer Valley GMA will occur in the future so that groundwater extraction can be managed within sustainable limits. Until this time, only the benefitted area part of the alluvial aquifer has been included as a groundwater asset.

Groundwater aquifers do occur elsewhere within the SEQ region; however, there are currently no models for these, and their storage volume could not be quantified in order to determine sustainable extraction limits.

A more detailed explanation is provided in line item 2.1 Water table aquifer and 2.2 Underlying aquifer.

The Statement of Water Assets and Water Liabilities for the groundwater store is shown in Table 5.

 

Table 5 Statement of Water Assets and Water Liabilities for the groundwater store 
Water assets

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

2 Groundwater    
2.1 Water table aquifer 9,340 9,340
2.2 Underlying aquifers
Total groundwater assets 9,340 9,340
     
Water liabilities    
6 Groundwater liability    
6.1 Groundwater allocation remaining 0 0
Total groundwater liabilities 0 0
     
Opening net water assets 9,340 9,340
Change in net water assets 0 0
Closing net water assets 9,340 9,340

 – = data not available.

Changes in water store

The Statement of Changes in Water Assets and Water Liabilities and the Statement of Water Flows for the groundwater store are provided in Table 6 and Table 7, respectively.

 

Table 6 Statement of Changes in water Assets and Water Liabilities for the groundwater store
Water asset increases

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

10 Groundwater increases    
10.6 Leakage from urban water system 27,613 28,662
Total groundwater increases 27,613 28,662
     
Water liability decreases    
14 Groundwater liability decreases    
14.1 Adjustment and fortfeiture of groundwater allocation 7,262 7,567
Total groundwater liability decreases 7,262 7,567
     
Water asset decreases    
18 Groundwater decreases    
18.8 Entitled extraction of non-allocated groundwater to users 3,064 2,003
18.9 Entitled extraction of non-allocated groundwater to urban water system 158 149
Total groundwater decreases 3,222 2,152
     
Water liability increases    
22 Groundwater liability increases    
22.1 Groundwater allocation announcements 9,340 9,340
Total groundwater liability increases 9,340 9,340
     
Balancing item – groundwater 22,313 24,737
     
Change in net water assets 0 0

 

 

Table 7 Statement of Water Flows for the groundwater store
Water inflows

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

10 Groundwater inflows    
10.6 Leakage from urban water system

                    27,613

                            28,662

Total groundwater inflows

                    27,613

                            28,662

     
Water outflows    
18 Groundwater outflows    
18.8 Entitled extraction of non-allocated groundwater to users

                     3,064

                                 2,003

18.9 Entitled extraction of non-allocated groundwater to urban water system

                    158 

                                 149

18.11 Entitled extraction of allocated groundwater to users

                     2,078

                              1,773

Total groundwater outflows

  5,300

                              3,925

     
Balancing item – groundwater

               22,313

                            24,737

     
Opening water storage

                      9,340

                              9,340

add/(less): Change in water storage

                           

                                  0 

Closing water storage

                      9,340

                              9,340

A schematic diagram representing all the inflows and outflows associated with the groundwater store in the SEQ region is provided in Figure 6. The inflow and outflow volumes for the groundwater store during the 2012–13 year are given in Table 7.


Figure 6 Schematic diagram of water inflows and outflows for the groundwater store within the South East Queensland region during the 2012–13 year; line item numbers are provided in brackets
Figure 6 Schematic diagram of water inflows and outflows for the groundwater store within the South East Queensland region during the 2012–13 year; line item numbers are provided in brackets


Allocations and extractions

Most of the extractions from the groundwater store were benefitted area extractions within the Central Lockyer Valley WSS in the Lockyer Valley GMA (line items 18.8 Entitled extraction of non-allocated groundwater to users and 18.11 Entitled extraction of allocated groundwater to users), which accounts for approximately 97% of the total groundwater extraction. Extraction data were not available for a number of other GMAs or for the non–benefitted area of Implementation Area 1 of the Lockyer Valley GMA.

Figure 7 shows that allocation extractions from aquifers during the 2012–13 year have increased by 35 % from last year. Although this year was a very wet year, the quantity and timing of rainfall in place may have required higher irrigation demand than last year. Only 3% of the total groundwater extraction came from line item 18.9 Non-allocated extraction of groundwater.

Figure 7 Graph of groundwater extractions from aquifers within the South East Queensland region during the 2012–13 year and 2011–12 comparison year; line item numbers are given in brackets
Figure 7 Graph of groundwater extractions from aquifers within the South East Queensland region during the 2012–13 year and 2011–12 comparison year; line item numbers are given in brackets

The allocation extractions are all associated with a water access entitlement. When an allocation is announced, an obligation (water liability) is created on the groundwater to deliver water to the users. As there is no carryover provision in the region, the portion of the announced allocations that were not diverted by the end of the year was forfeited.

The entitlement, allocation announcement, and forfeiture for each of these water rights during the 2012–13 year are provided in the Water rights, entitlements, allocations and trade note, in the 'Groundwater rights'.

Balancing item

This volume represents the volume necessary to reconcile the opening and closing balances of the groundwater store with the physical water inflows and outflows.

The balancing item was calculated across the whole SEQ region, not just the individual aquifers included as the groundwater asset.

The balancing item was calculated according to Table 8.

 

Table 8 Balancing item for the groundwater store for the 2012–13 year

Account

Volume (ML)

Opening balance 1 July 2012

9,340

Total groundwater inflows (see Table 7)

27,613

Total groundwater outflows (see Table 7)

(5,300)

Closing balance 30 June 2013

(9,340)

Balancing item – groundwater store

22,313

 

The calculation of the water balance on the groundwater store yielded a balancing item of 22,313 ML, approximately 81% of the total groundwater inflows during the 2012–13 year.

This large balancing item value is primarily due to the groundwater asset and flows being calculated in ways that do not allow them to reconcile on an annual basis:

  • The groundwater asset is quantified as the average long-term groundwater volume available for extraction without adversely impacting the system. This value is constant during the year, unless its scope (number of groundwater areas included) or quantification approach has changed.
  • In contrast, inflows and outflows represent measured, estimated or modelled yearly values that vary depending on climatic conditions, extractions and so on.

For the 2012–13 year, the groundwater asset value was estimated as the nominal volume (entitled volumetric limit) of water in the benefitted area part of the alluvial aquifer in the Central Lockyer WSS only, whereas the inflows and outflows associated with groundwater were for the entire SEQ region.

Another factor explaining the large balancing item is non-availability of relevant data on groundwater recharge and discharge in the calculations of the groundwater inflows and outflows (Table 7). 

This value of balancing item is 2,424 ML lower in magnitude than that reported in the 2012 Account (Table 7). This can be attributed due to lower groundwater inflows and higher outflows.

Urban water system


Background

Background information on the urban water system within the South East Queensland (SEQ) region is available in the 'Contextual information' under Other water resources and distribution systems.

Water in store

The Statement of Water Assets and Water Liabilities for the urban water system (Table 9) shows that the volume of water in the urban water system changed marginally during the 2012–13 year in the SEQ region.  

Table 9 Statement of Water Assets and Water Liabilities for the urban water system
Water assets

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

3 Urban water system    
3.1 Urban water supply system

  3,727

                             2,842

Total urban water system assets

      3,727

                              2,842

     
Opening net water assets

          2,842

                              2,094

Change in net water assets

            885

                                  748

Closing net water assets

    3,727

                              2,842

Table 9 shows that, for the urban water system in the SEQ region, only the volume of water contained in the urban water supply system could be quantified. The volume only includes bulk mains and does not include balancing tanks (locally called reservoirs) or distribution pipe networks. It is expected that the volume shown would be a significant underestimate of the total asset, which may be two to three times this volume. As balancing tanks have not been included, the volume in the urban system remains relatively constant over time as all pressurised pipes are required to remain completely full for the supply system to operate. A slight increase was expected due to upgrades to the network and the addition of new pipes to service new areas.

Volumes associated with other supply and collection systems could not be quantified in the SEQ due to lack of data. The recycled water supply system volume, being much smaller in extent than the urban water supply system, would have a much smaller volume. The wastewater collection system may cover a similar extent to the urban water supply system and have a similar capacity, although the volume would be smaller due to gravity sewers operating as part pipe flow rather than full pipe flow as occurs in the urban water supply system.

The extent of the urban water supply and collection systems within the SEQ region can be seen in the Seqwater infrastructure map (Seqwater 2013a). 

Changes in water store

The Statement of Changes in Water Assets and Water Liabilities and the Statement of Water Flows for the urban water system are provided in Table 10 and Table 11, respectively.  

 

Table 10 Statement of Changes in Water Assets and Water Liabilities for the urban water system
Water asset increases

Volume at 30
June
2013

Volume at 30
June
2012

11 Urban water system increases    
11.2 Entitled diversion of non-allocated surface water to urban water system

               3,357

                           4,383

11.3 Entitled extraction of non-allocated groundwater to urban water system

                   158

                              149

11.4 Wastewater collected

                      244,668

                        246,055

11.5 Delivery of water from outside region to urban water system

               24,514

                          22,902

11.6 Delivery of desalinated water to urban water system

                       2,805 

                          3,427

11.18 Increase of urban claim on surface water

   442,826

                        442,826

Total urban water system increases

                  718,328

                        719,742

     
Water asset decreases    
19 Urban water system decreases    
19.2 Leakage to landscape

0

19.3 Leakage to groundwater 27,613

28,662

19.4 Delivery to urban water system users 236,941 259,039
19.5 Discharge from urban water system to surface water 39,413 62,517
19.7 Wastewater discharge outside of region 183,894 203,228
19.8 Other wastewater discharge 892 645 
19.11 Transfer of water outside of region 419 3,012
19.17 Adjustment and forfeiture of urban claim on surface water 221,763 230,474
19.20 Other urban water system decreases


7,217


0

Total urban water system decreases 718,152 787,577
     
Balancing item – urban water system (709) (68,583)
     
Change in net water assets 885 748

  

Table 11 Statement of Water Flows for the urban water system
Water inflows

Volume at 30 June
2013
ML

Volume at 30 June
2012
ML

11 Urban water system inflows    
11.2 Entitled diversion of non-allocated surface water to urban water system

             3,357

                              4,383

11.3 Entitled extraction of non-allocated groundwater to urban water system

   158

                                 149

11.4 Wastewater collected

             244,668

                          246,055

11.5 Delivery of water from outside region to urban water system

    24,514

                           22,902

11.6 Delivery of desalinated water to urban water system

     2,805

                            3,427

11.12 Entitled diversion of allocated surface water to urban water system

   221,063

                          212,352

Total urban water system inflows

                 496,565 

                         489,268

     
Water outflows    
19 Urban water system outflows    
19.2 Leakage to landscape

                          

                                0

19.3 leakage to groundwater

27,613

                            28,662

19.4 Delivery to urban water system users

    236,941

                          259,039

19.5 Discharge from urban water system to surface water

                    39,413

                            62,517

19.7 Wastewater discharge outside of region

                   183,894

                         203,228

19.8 Other wastewater discharge

                       892

                                 645

19.11 Transfer of water outside of region

                   419

                              3,012

19.20 Other urban water system decreases


7,217


0

Total urban water system outflows

                  496,389

                         557,103

     
Balancing item – urban water system

              (709)

                           (68,583)

     
Opening water storage

                     2,842

                              2,094

add/(less): Change in water storage

                     885

                                  748

Closing water storage

                   3,727

                              2,842

 

A schematic diagram representing all the inflows and outflows associated with the urban water system in the SEQ region is provided in Figure 8.


Figure 8 Schematic diagram of water inflows and outflows for the urban water store within the South East Queensland region during the 2012-13 year; line item numbers are provided in brackets
Figure 8 Schematic diagram of water inflows and outflows for the urban water store within the South East Queensland region during the 2012-13 year; line item numbers are provided in brackets


Water sources, allocations and diversions

There are three main sources of water for the urban water supply system:

  • surface water
  • groundwater
  • desalinated water.

In the SEQ region the urban water rights for the SEQ water grid are owned and managed by Seqwater. The Seqwater holds both supplemented high-security surface water entitlements (see line item 32.2 Surface water access entitlement for non-allocated diversions) and unsupplemented surface water licences (see line item 32.3 Surface water access entitlement for allocated diversion).

Additional information on the types of surface water and groundwater entitlements used to provide the urban water supply system with water can be found in the Water rights, entitlements, allocations and restrictions note.

Regulated (supplemented) entitlements divert water from various water supply schemes managed by Seqwater (as the resource operations licence holder). The diversions of allocations based on regulated entitlements are reported under line item 11.12 Entitled diversion of allocated surface water to urban water system. Information on allocation announcement (made under line item 32.3 Surface water access entitlement for allocated diversions) for this line item are available in line item 11.18 Increase of urban claim on surface water.

Unregulated (unsupplemented) licences allow the Seqwater to divert water from various weirs, rivers, channels and surface water storages subject to various rules relating to river/storage heights, flows or water qualities. Rules are stipulated on individual licences, which can be found in Department of Natural Resources and Mines (2013b, 2013c, 2013d)  resource operations plans (ROPs). Diversions based on these licences are reported under line item 11.2 Entitled diversion of non–allocated surface water to urban water system (made under line item 32.2 Surface water access entitlement for non–allocated diversions).

In addition to these two sources, the Seqwater also extracts groundwater under basic rights from various bore fields in the SEQ region that were developed to supplement supplies during the drought that occurred up until 2009. Extraction from these borefields has declined since high rainfalls resulted in surface water sources becoming more reliable. The volume extracted from borefields in the SEQ region is reported under line item 11.3 Non–allocated diversion of groundwater (made under line item 33.2 Groundwater access entitlement for non–allocated extractions).

Desalination has been developed in the SEQ region as a new water source to supplement surface water supplies. This was developed as part of the SEQ Regional Drought Strategy, with the Gold Coast desalination plant having a capacity of 133 ML/day. Due to the increased yield from surface water storages during the 2012–13 year there has been a decrease in the volume sourced from the plant in 2012–13 compared to previous years.

The SEQ water grid extends to the north and east of the National Water Account's SEQ region. Various water grid sources outside of the region supply water into the region. Groundwater water treatment plants (WTPs) on Stradbroke Island (via the Eastern Pipeline Interconnector) and various surface water WTPs in the Sunshine Coast (via the Northern Pipeline Interconnector) supply water into the SEQ region. Such volumes received from outside sources are reported under line item 11.5 Delivery of water from outside region.

Figure 9 shows that the SEQ region relied heavily on allocated diversions from surface water to meet urban demand (88% of source water). Desalination constituted around 1% and transfers into the region around 10%, while unregulated surface water supplies accounted for around 1% of the total urban demand. It is seen that allocated surface water diversion (line item 11.12), delivery of water from outside region (line item 11.5) and non-allocated groundwater extraction (line item 11.3) increased in 2012-13 compared to last year; whereas,  non-allocated surface water diversion (line item 11.2) and delivery of desalinated water (line item 11.6) decreased in the 2012-13 year.

Figure 9 Sources of water for South East Queensland's urban water supply system; line item numbers are given in brackets
Figure 9 Sources of water for South East Queensland's urban water supply system; line item numbers are given in brackets



Urban water restrictions


The SEQ region was on permanent water conservation measures (PWCM) from 1 December 2009. On April 2012, the PWCM were amended to remove a number of mainly non-residential restrictions which already existed elsewhere in the legislation or were shown to have been put in place. The residential restrictions only had minor changes which would not have significantly impacted on the overall consumption. The PWCM were then lifted on 1 January 2013 as a result of the abolition of the Queensland Water Commission.


Discharge from the urban wastewater collection system

Wastewater collected (line item 11.4) in the SEQ region was treated and disposed either inside or outside the region, or treated and provided for use either inside or outside the region (Figure 10). Majority of treated wastewater was discharged to sea (part of line item 19.7) followed by surface water (part of line item 19.5) and landscape ( line item 19.8). Treated wastewater was also used as recycled water (part of line item 19.4) and transferred outside of the region (line item 19.11). Approximately 7% of the total wastewater collected was used as recycled water in 2012-13, which was less than 22% of the previous year's total. 

Figure 10 Wastewater discharge, export and recycled water use in the South East Queensland region; line item numbers are given in brackets
Figure 10 Wastewater discharge, export and recycled water use in the South East Queensland region; line item numbers are given in brackets


From Figure 10, it can be clearly seen that the majority of wastewater is discharged out of the region, with surface water being the second most common receiving medium.


Balancing item

This volume represents the volume necessary to reconcile the opening and closing balances of the urban water system store with the physical water inflows and outflows. The balancing item was calculated according to Table 12.

Table 12 Balancing item for the urban water system store for the 2012–13 year

Account

Volume (ML)

Opening balance at 1 July 2012

          2,842

Total Urban water system inflows (see Table 11) 

496,565

Total urban water system outflows (see Table 11)

(496,389)

Closing balance at 30 June 2013

(3,727)

Balancing item – urban water system store

                 (709) 

 


The calculation of the water balance on the urban water system store yielded a balancing item of -709 ML. The difference between total urban water system inflows and outflows is negligible. 

It is likely that the balancing item can be attributed to uncertainty associated with consumer meter readings, lack of leakage data for off-grid water supply systems and uncertainty in estimating leakage.

Off-channel storages

Purpose

The purpose of this note is to report on water held in off-channel water storages within the South East Queensland (SEQ) region during the 2012–13 year. Where available, water flows to and from off-channel water storages are reported here. Water held in off-channel water storages is not reported in the water accounting statements because the statements report only on water resources yet to be shared. Water held in off-channel water storages is considered to be abstracted from the shared pool of water resources and, as such, is not included as part of the region's water assets (see Scope of the South East Queensland region water account in the 'Contextual information').

Off-channel storages influence water assets and water liabilities recognised in the water accounting statements as they harvest water from the landscape and thus reduce groundwater recharge and runoff into surface water.

Background

A description of SEQ's off-channel storages is provided in the Other water resources and distribution systems section of the 'Contextual information'.

Water in store

The number of off-channel storages was estimated by Department of Environment and Resource Management (DERM) in 2010 using the following criteria:

  • water storage must have a surface area greater than 0.25 ha
  • water storage must be human-made.

The data is not intended as a complete count of off-channel storages, but is an indication of the number of larger storages within each water resource plan area. A reliable complete count of all off-channel storages was not readily available at the time of publication.

Off-channel storages were identified using remote sensing with 30 m pixels, and therefore some storages may have been omitted during the identification process. All off-channel storages identified have been sighted and their existence confirmed.

A water depth of 2 m was used to estimate the off-channel storage volume (Table 13). Although this was an arbitrary volume recommended by DERM, it would be expected that most off-channel storages would have been relatively full at the start and end of the 2012–13 year as well above-average rainfall was experienced prior to and during the 2012–13 year (see Climate overview).

Table 13 Estimated storage volume and number of off-channel storages in the South East Queensland region.
Water resource plan (WRP) area

River system

Count

Total surface area

Volume

Quantity

Percentage of total

(m2)

(ML)

Gold Coast Coomera River 93 5 3,389,647 6,779
Total Gold Coast WRP area 93 5 3,389,647 6,779
Logan Basin Albert River 102 6 1,671,718 3,344
Logan River 371 22 4,167,129 8,334
Total Logan Basin WRP area 473 28 5,838,847 11,678
Moreton Bremer River 302 18 4,808,992 9,618
Brisbane River 156 9 2,770,688 5,541
Caboolture River 87 5 788,129 1,576
Lockyer River 320 19 7,101,810 14,204
Maroochy River 116 7 1,884,659 3,769
North Pine 53 3 1,611,937 3,224
South Pine 19 1 544,028 1,088
Stanley River 77 5 801,017 1,603
Total Moreton WRP area 1,130 67 20,311,260 40,623
Total SEQ region 1,696 100 29,539,754 59,080

Off-channel storage inflows and outflows

The volume of inflows and outflows from off-channel storages could not be quantified in a way that is complete, neutral, and free from material error due to the lack of both data and a suitable quantification approach.