About the area
The Yarra River flows from forested mountains in the east of the basin through the City of Melbourne to Port Phillip Bay.
Average annual rainfall in the upper Yarra is over 1,200 mm, although the western side of the basin receives below 600 mm on average.
In combination with the Thomson River, Bunyip and Tarago Rivers, Silver and Wallaby creeks and the Victorian Desalination Plant; the Yarra River provides Melbourne’s water supply.
More information on water management and accounting is detailed in Water
2022-23 overview
Available water
Catchment inflow was higher than the previous year.
Licensed diversion restrictions
There were fewer restrictions on licensed diversions than the previous year.
Water use
A similar volume of water was diverted for consumptive purposes to the previous year.
When compared to the previous year, in 2022-23:
- more rainfall was received, catchment inflow was higher and storage levels peaked and declined at higher levels
- there were fewer restrictions on licensed diversions from unregulated streams
- a similar volume of water was diverted from the basin for consumptive uses
- more water was diverted for environmental uses.
Climate
Rainfall
In 2022-23, rainfall in the Yarra basin was very much above the long-term average across most of the basin, and higher than the previous year. Rainfall was:
- above average along the western border of the basin from around Greenvale reservoir to the coast, and in a region in the Yarra Ranges around Warburton.
- very much above average over all other areas of the basin.
Figure 1 displays the rainfall received in 2022-23 compared to the long-term average (1975-2023).
Figure 1: Rainfall deciles, Yarra basin
Sourced from the Australian Bureau of Meteorology
Desalinated water
Another order for water from the Victorian Desalination Project was made for 2022-23 by the Minister for Water.
The total volume delivered to 30 June 2023 was 4.1 GL, less than the previous year.
River basin water balance
This section describes the known and estimated inflows, outflows and change of storage volumes in the basin.
Of the total inflows, 74% flowed out into Port Phillip Bay in 2022-23.
Water balance table
The table below shows the total volumes of water available and supplied from water resources in the Yarra basin in 2022-23.
Table 1: Water balance, Yarra basin
Major on-stream storages
Major - greater than 1,000 ML - on-stream storages in the Yarra basin are included in the water balance.
Melbourne Water operates 8 major storages within the Yarra basin. Water is harvested by the Upper Yarra, O’Shannassy and Maroondah reservoirs. Sugarloaf and Yan Yean reservoirs are off-stream storages but have dual roles: to harvest water and to act as seasonal balancing reservoirs. Silvan and Greenvale reservoirs are off-stream storages and act as seasonal balancing reservoirs.
Storage levels
Major on-stream storage levels in the Yarra basin reached 74% on 30 June 2023.
Similar to the previous year
Storage levels were 72% on 30 June 2022.
Table 2: Storage levels, Yarra basin
Inflows
Catchment inflow
Catchment inflow represents the volume of water flowing into the waterways of a basin. It is calculated as the total outflows and change in storage minus the known inflows.
Above average inflows of 1,707,922 ML were received (179% of the long-term average of 954,200 ML), more than the previous year (124% of the long-term average). This was reflective of the very much above average rainfall received across the basin in 2022-23.
Above average inflow received
Catchment inflow was 179% of the long-term average of 954,200 ML.
More water received than the previous year
This was higher than the previous year (124% of the long-term average).
Wastewater treatment plants
Water treated at wastewater treatment plants can be used to supplement water available in the basin. Water discharged to waterways from treatment plants is included as an inflow to the water balance.
Information on treatment plants is reported in the water supply local reports for the water corporation responsible for managing the plant.
In this basin, wastewater treatment plants are managed by Yarra Valley Water.
Outflows
Diversions
In 2022-23, 463,479 ML of surface water was diverted for consumptive and environmental uses. This was similar to the 506,208 ML diverted in the previous year.
Small catchment dams
Water harvested, used and lost by small catchment dams (farm dams) is included in the water balance.
Table 3: Small catchment dams, Yarra basin
Entitlements and compliance
Entitlements provide the basis for how water is shared in the basin.
Melbourne Water holds a bulk entitlement to surface water in the Yarra basin. This entitlement is one of four that contribute to the Greater Yarra system - Thomson River Pool, which primarily supplies Melbourne and supports regional urban water corporations, including Barwon Water, Greater Western Water (formerly City West Water and Western Water), South Gippsland Water and Westernport Water.
Melbourne headworks system: Greater Yarra system – Thomson River Pool
Melbourne's water has traditionally been sourced from the Yarra, Thomson, Bunyip (Bunyip and Tarago rivers) and Goulburn (Silver and Wallaby Creeks) basins. Since the Millennium Drought, major investments in infrastructure have brought other water sources online to support Melbourne's water security. These include the North-South Pipeline, which can bring water from the Goulburn River to be stored in Sugarloaf Reservoir and used to supply Melbourne. However, it can only be used once Melbourne’s storage levels fall below 30% and other conditions are met. Another major investment has been the Victorian Desalination Project near Wonthaggi.
Surface water sourced from the Yarra, Thomson, Bunyip (Bunyip and Tarago Rivers) and Goulburn (Silver and Wallaby Creeks) basins is known collectively as the Greater Yarra system - Thomson River Pool.
Melbourne Water holds bulk entitlements to surface water in the Thomson River, Yarra River, Tarago River and Silver and Wallaby Creeks. It uses this water to supply the bulk entitlement holders in the Greater Yarra system - Thomson River Pool: Greater Western Water (formerly City West Water and Western Water), South East Water, Yarra Valley Water, Barwon Water, South Gippsland Water and Westernport Water (see Table 4).
Melbourne Water’s Yarra River, Thomson River and Silver and Wallaby Creeks bulk entitlements each specify diversion limits on the volume of water that may be taken annually from the respective waterways. Melbourne Water makes an allocation at the beginning of each month to distribute the available water to entitlement holders according to their entitlement share.
In 2022-23, the allocation reached 138.6%, higher than in the previous year when it reached 104%. In the Melbourne System there is no bulk entitlement or system capacity constraint that limits the allocation to 100%.
Volumes of water carried over, allocated, traded and used against each of the bulk entitlements are provided in Table 5.
Volumes of water taken from the river systems to supply the Greater Yarra system - Thomson River Pool are also reported on each individual river basin local report, while deliveries to customers by the Melbourne retailers - South East Water, Yarra Valley Water and Greater Western Water (formerly City West Water and Western Water) - are accounted for in the water supply local reports.
Table 4: Greater Yarra System - Thomson River Pool bulk entitlement shares at 30 June
Table 5: Available water and take under entitlements - Greater Yarra system-Thomson River Pool
Victorian Desalination Project
Desalinated seawater from the Victorian Desalination Project near Wonthaggi may be sourced to supplement surface water supplies from the Melbourne headworks system. The 3 metropolitan water corporations - Greater Western Water (formerly City West Water and Western Water), Yarra Valley Water and South East Water - hold the bulk entitlements to this desalinated seawater. These entitlements are shown in Table 6.
In 2022-23, 4.1 GL of water was delivered from the Victorian Desalination Project, and this water was allocated to the 3 Melbourne retailers in accordance with their bulk entitlements. The volume delivered is included as an inflow into the Yarra basin, as it represents an inflow of water into part of the Melbourne headworks system in the Yarra basin.
Table 6: Desalinated water bulk entitlements at 30 June
Entitlement volumes
Rights to water in the Yarra basin are shown in Table 7.
Entitlement volumes represent a maximum volume of water that can be taken in a one-year period. The volume available in a particular year is dependent on the rules for allocating water set out in the entitlement and the seasonal conditions in that year, which can vary. The rules for allocating water under an entitlement differ between entitlements and systems. This affects the ability and likelihood of water being taken in a particular year.
Table 7: Annual entitlement volumes at 30 June, Yarra basin
Available water and take under entitlements
Total water available under entitlements represents the volume of water that was available to be taken by entitlement holders in 2022-23. The volume includes carryover from the previous year, seasonal allocations and net trade into the basin.
Water taken
There was 339,347 ML taken under entitlements in 2022-23, similar to the previous year (329,122 ML).
Restrictions on licensed diversions from unregulated rivers
In the Yarra basin, licensed diversions from unregulated streams had:
- a total of 9 stream sections restricted or banned at some point during 2022-23
- a peak of 7 restrictions or bans during February 2023. This was fewer than the peak of 10 during the previous year
- only 3 bans at the end of June 2023
- no restrictions or bans on 17 stream sections for the whole of 2022-23.
Available water and take table
This table shows the volume of available water and the volume taken under entitlements in 2022-23.
More information on available water and take has been detailed in How we account for surface
In 2022-23, a similar volume of water was taken under entitlements as the previous year.
Table 8: Available water and take under entitlements, Yarra basin
Compliance
Compliance against water entitlements is reported for this basin in 3 areas:
- entitlement issued: that the volume of entitlements issued in a basin does not exceed formal caps, and has not increased without appropriate approvals
- water taken: that the volume of water taken during the year does not exceed the volume considered to be available for consumptive and/or in-stream use during that year
- bulk entitlement provisions: that holders of entitlements do not breach any provisions that are documented in their bulk entitlement orders.
Total entitlement volume
There was no net increase in the total entitlement volume from the previous year.
Total volume diverted
The total volume diverted under entitlements (339,347 ML) was within the volume available for the year (462,116 ML).
Individual bulk entitlements
No individual bulk entitlement holder took more than the annual volume made available to them.
Exceptions to compliance
Individual bulk entitlement holders complied with all provisions in their entitlements.
Water for the environment
Environmental watering sites
Environmental watering sites and environmental values in the Yarra basin that depend on water for the environment include:
- Australian grayling, river blackfish, Macquarie perch and numerous billabongs and wetlands
- the Yarra River between Warburton and Warrandyte, which has been identified as a Victorian heritage river and is a priority for water for the environment
- billabongs on the lower Yarra River floodplain between Heidelberg and Dights Falls as well as on the reach around Yarra Glen, which support distinct vegetation communities and provide foraging and breeding habitat for waterbirds and frogs.
Environmental water reserve
In 2022-23, water for the environment in the Yarra basin comprised:
- the Yarra River Environmental Entitlement 2006, which includes 17,000 ML of high-reliability entitlement and 55 ML of unregulated surface water entitlement held by the VEWH
- water set aside for the environment through the operation of:
- 7 streamflow management plans
- passing flow conditions on the Yarra River Environmental Entitlement 2006
- passing flow conditions on licensed diversions
- all other water in the basin not allocated for consumptive uses: this water also provides social, recreational and cultural benefits.
Environmental water use
In 2022-23, a total of 7,008 ML of environmental water was delivered in the Yarra basin: 66 ML of this was diverted off-stream.
Management responsibilities
Management of water in the Yarra basin is undertaken by various parties.
| Authority | Management responsibilities |
|---|---|
| Melbourne Water |
|
| Yarra Valley Water |
|
| South East Water |
|
| Greater Western Water (formerly City West Water and Western Water) |
|
| Goulburn Valley Water |
|
| Water supply system | 2021-22 (ML) | 2022-23 (ML) |
|---|---|---|
| Melbourne Water | 491,158 | 445,840 |
