Perth: Water access and use
Water rights, entitlements, allocations and restrictions
Introduction
This note provides information about the water access rights granted by jurisdictions to the users of the region's water resources and the associated allocation announcements and abstractions.
The 2015 Account acknowledges that the legislative water resource management frameworks relating to Australian water rights vary greatly across jurisdictions, sometimes making comparisons difficult. To facilitate meaningful comparisons between the 2015 water accounting reports, the Bureau of Meteorology has developed and applied an accounting concept to classify and report water entitlements within a water asset/water liability framework.
According to that framework, water rights for the Perth region for the 2014–15 year have been classified as shown below.
Surface water rights
Surface water rights in the Perth region during the 2014–15 year refer to surface water supply for:
- individual users—38,556 ML
- urban water system—247,950 ML
- irrigation scheme—65,700 ML.
Surface water rights for the urban water system and the irrigation scheme relate to entitlements to divert water from storages to the Perth region's Integrated Water Supply Scheme and the Harvey Water Irrigation Area respectively.
In the Perth region, surface water allocations for individual users and the urban water system are equal to 100% of the water access entitlement; however, allocations for the irrigation scheme are a percentage of the entitlement, which are announced at the start of the irrigation season on 1 October each year.
The volume of surface water entitlements, corresponding allocations, and diversions for the 2014–15 year compared with the 2013–14 year are shown in Figure N30. The percentage shows the ratio of diversion to the water entitlement.
Note that water allocations and diversions related to the urban water system and irrigation schemes appear in the Surface water note; however, they do not appear in the water accounting statements because they are transactions that occurred within the region. These transactions did not impact the region's total water assets and water liabilities.
Figure N30 Surface water access entitlements, allocations and diversions in the Perth region for the 2013–14 and 2014–15 years
Figure N30 shows that the allocation for surface water diversion to the irrigation scheme increased from the previous year by approximately 20%, reflecting the increased availability of water in the irrigation supply storages; however, despite the increased allocation, surface water diversions to the irrigation scheme during the 2014–15 year marginally decreased from the previous year.
Allocations for the urban water system during the 2014–15 year remain unchanged from the previous year; however, diversions to the urban water system increased. It should be noted that surface water diversion to the urban water system is a gross volume, that is, a portion of this water is made up of groundwater and desalinated water produced in the winter and then transferred to storages for future use. Net surface water diversion to the urban water system during the 2014–15 year (47,519 ML) is actually similar to previous years (see Urban water system note).
Allocations for individual users during the 2014–15 year increased by almost 5,000 ML from the previous year (Figure N30). This can be attributed to an increase in annual entitlement to a large mining company licence within the region during the year.
There are approximately 200 individual users that primarily source water from rivers within the region for mining and industrial purposes. The water supply licences are divided into licence entitlement purposes. Figure N31 shows the annual allocation announcement to individual users for each licence purpose for the 2014–15 year changed compared with that of the previous year. In particular, allocations for mining purposes increased by 30% as a result of the licence entitlement increase mentioned above.
Figure N31 Surface water allocation to individual users for each licence purpose for the 2014–15 and 2013–14 years
Groundwater rights
Groundwater rights in the Perth region during the 2014–15 year refer to groundwater supply for:
- individual users—287,753 ML
- urban water system—129,019 ML.
Groundwater rights for the urban water system relate to entitlements to extract water from aquifers to the Perth region's Integrated Water Supply Scheme.
In the Perth region, groundwater allocations were equal to 100% of the water access entitlement. The volumes of groundwater allocation and extraction for the 2014–15 year compared with the 2013–14 year are shown in Figure N32. The percentage shows the ratio of extraction to the allocation announcement.
Note that water allocations and abstractions related to the urban water system appear in the Groundwater note; however, they do not appear in the water accounting statements because they are transactions that occurred within the region. These transactions did not impact the region's total water assets and water liabilities.
Figure N32 Groundwater allocations and extractions in the Perth region for the 2013–14 and 2014–15 years
Figure N32 shows that groundwater allocations for the urban water system during the 2014–15 year decreased slightly from the previous year. This decreasing trend of recent years coincides with the increased production of desalinated water to the urban water system and the recognition of the need to reduce extractions to a more sustainable level. Similarly, extractions to the urban water system also decreased slightly from the previous year.
Groundwater allocations and extractions for individual users during the 2014–15 year were relatively similar to the previous year. The relatively high percentage of extraction to allocation for individual users is because the majority of individual licence holders abstractions are not measured and are assumed equal to the licence holders' allocations.
There are approximately 6,000 individual users that source water from aquifers within the region. The water supply licences are divided into licence entitlement purposes. Figure N33 shows the annual allocation announcement to individual users for each licence purpose for the 2014–15 year changed little from that of the previous year.
Figure N33 Groundwater allocation to individual users for each licence purpose for the 2014–15 and 2013–14 years
Water restrictions
During the 2014–15 year, urban-water users and garden-bore users were on a sprinkler roster.
Whilst on the sprinkler roster, urban-water users connected to the Perth region's Integrated Water Supply Scheme were able to use their sprinklers two days per week. Residents with their own garden bore had an additional sprinkler day per week. The sprinkler days were determined by the last digit of the user's street number and sprinklers must be used before 9am and after 6pm. There is a total sprinkler ban for the winter months (June–August).
These water restrictions have been in place in the region since November 2010. For more information, refer to the Bureau of Meteorology's Water restriction website.
Water market activity
In Western Australia, water entitlement trades and transfers can only occur within the same water management area (see the Trades and water rights transfers section in the 'Contextual information').
Trades and transfers are defined as water entitlements that are permanently transferred to another licence holder. A trade is where the new licence holder will abstract water from a different location; a transfer is where water abstraction will occur from the same location. An agreement is a temporary transfer of a licence water entitlement to another licence holder (also referred to as a temporary transaction). More information on water entitlement transactions can be found on the Department of Water website.
Table N38 shows the trades and transfers of licence entitlements that occurred in the Perth region during the 2014–15 year. Most of the water market activity within the Perth region during the year was related to groundwater entitlement trade.
| Transaction type | Number of licences | Volume ML |
| Surface water entitlement transactions within region | ||
| transfer | 3 | 21 |
| agreement | 1 | 25 |
| Groundwater entitlement transactions within region | ||
| trade | 35 | 637 |
| transfer | 83 | 3,048 |
| agreement | 18 | 876 |
| Total | 173 | 4,607 |
Water use
Economic, social and cultural benefit
Surface water and groundwater resources within the Perth region are used for public water supply, irrigation scheme supply, as well as private water supply for purposes such as agriculture, industry, and mining. For a summary of the water volumes allocated for various economic purposes within the region, including the actual volumes abstracted, refer to Surface water rights and Groundwater rights above.
Water is released from Harvey Reservoir during the irrigation season (generally November–May) to ensure that there is flow along Harvey River downstream of the reservoir. Along with irrigation supply and environmental requirements, it is considered important that Harvey River has flow for aesthetic reasons, primarily because this region of the Harvey River is a tourist precinct.
Water regimes required to support cultural values are not quantitatively defined in allocation plans (see the Cultural water management section of the 'Contextual information'); however, the cultural values are considered within the environmental water provisions.
Environmental benefit
Introduction
Water for environmental benefit in the Perth region is provided according to two different environmental water management scenarios:
- planned, partly regulated surface water
- planned groundwater.
Planned, partly regulated surface water
The dominant feature of environmental water management in this scenario is the ability to control or influence flow by operational releases from storages. For the Perth region, these environmental water releases are also referred to as riparian releases.
Environmental water legislation
Environmental water provisions in the Perth region are currently only defined for the Canning River. These provisions are outlined in the Middle Canning River Surface Water Allocation Plan.
The plan outlines a flow regime required to maintain current ecological conditions in the lower Canning River. These ecological requirements were developed by Radin et al. (2010), and include the maintenance of:
- flow connectivity
- pool depth as refuge habitat
- a minimum flow over riffles for macro-invertebrates
- prevention of anoxic conditions in pools.
Environmental releases are also made from other rivers and storages in the region (e.g., Serpentine River and Wungong Brook) but there are no statutory requirements associated with these releases.
Environmental water provisionsEnvironmental water releases are made during the drier months between November and May from surface water storages and water mains along the Canning River. There are six release points along the river, and these releases make up most of the river's summer baseflow. The location of these release points are given in Figure N34 and Chapter 5 of the Middle Canning River Surface Water Allocation Plan.
The Water Corporation operates the storages and manages the release of water from the environmental release points. The Department of Water monitors the flow along the Canning River at the Seaforth gauging station (Station 616027: see Figure N34) to ensure that adequate baseflow is being maintained.
Figure N34 Middle Canning River environmental release points
Figure N35 shows the required flow regime at the Seaforth gauging station (616027) throughout the standard summer-flow release period. The release schedule commences when flow at the Seaforth station falls below 9.3 ML/day for 3 consecutive days in late spring. Once started, the releases must meet the required flow threshold, that is, the minimum daily flow measurement at the Seaforth gauging station must remain above 1.8 ML/day during the summer period. Releases are ceased when 40 mm of rainfall are recorded after 1 April at the Bureau of Meteorology's Gosnells weather station.
Figure N35 Example water provisions for the Canning River; required baseflows and higher flow pulses are also shown
In addition, there is also provision for up to three higher volume 'pulse' flows to aid upstream fish migration during summer. These pulse flows are scheduled to occur between November and January, and are generally initiated when flow at the Seaforth gauging station (Figure N34) is less than 9.3 ML/day for 15 consecutive days.
A more detailed description of these environmental water release schedules are provided in Appendix B of the Middle Canning River Surface Water Allocation Plan, including variations to the release schedule for low rainfall years.
Environmental water outcomes
The mean daily flow at the Seaforth gauging station along the Canning River during the summer period for the 2014–15 year is shown in Figure N36.
Figure N36 Daily flow in the Canning River compared with the required flow regime during the 2014–15 year
The summer-flow release schedule for the Canning River commenced early-November 2014 after three consecutive days of less than 9.3 ML/day of flow was observed at the Seaforth station (Figure N36). The release schedule ceased on 4 May 2015 when cumulative rainfall (since 1 April) at Gosnells weather station exceeded 40 mm.
Figure 36 shows that flow in the Canning River exceeded the minimum baseflow requirements for the entire summer period. There were also three pulse flows that occurred in the river during November–January, indicating that the higher flow pulse requirement outlined in the water provisions was also met.
Planned groundwater
In the Perth region, limiting the groundwater extractions is the main instrument used to meet the requirements of the groundwater-dependent ecosystems. The Department of Water considers the water requirements of groundwater-dependent ecosystems when setting limits to groundwater extractions in the allocation planning process.
Environmental water legislation
Environmental water provisions in the Perth region are currently defined for the Gnangara and Jandakot groundwater systems. These provisions are now ministerial guidelines under the Western Australian Environmental Protection Act 1986 and are based on water level criteria set for representative sites in the area. The Department of Water monitors these sites to determine compliance with criteria; however, no information about the environmental water outcomes was available to be included in this report.