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, though the western side of the basin receives below 600 mm on average.
- In combination with the Thomson River, the Victorian Desalination Plant and to a lesser extent the Goulburn River, the Yarra provides Melbourne’s water supply.
More information on water management and accounting is detailed in Water .
2021-22 overview
Available water
Catchment inflow was higher than the previous year.
Licensed diversion restrictions
Restrictions on licensed diversions were similar to the previous year.
Water use
More water was diverted for consumptive purposes than the previous year.
When compared to the previous year, in 2021-22:
- less rainfall was received, but catchment inflow was higher and storage levels peaked and declined at higher levels
- restrictions on licensed diversions from unregulated streams were similar to the previous year
- more water was diverted from the basin for consumptive uses
- less water was diverted for environmental uses.
Climate
Rainfall
In 2021-22, rainfall in the Yarra basin was average across most of the basin, lower than the previous year.
Desalinated water
Another order for water from the Victorian Desalination Project was made for 2021-22 by the Minister for Water.
The total volume delivered to 30 June 2022 was 125 GL, the same as in the previous year.
River basin water balance
In 2021-22, 506,208 ML of surface water was diverted for consumptive uses: town, domestic and stock, irrigation and commercial supply. This was more than the 447,196 ML diverted in the previous year.
Water balance table
The table below shows the total volumes of water available and supplied from water resources in the Yarra basin in 2021-22.
Table 1: Water balance, Yarra basin
Storages
Major — greater than 1,000 ML — on-stream storages in the Yarra basin are included in the water balance.
Melbourne Water operates eight 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 72% on 30 June 2022.
Similar to the previous year
Storage levels were 70% on 30 June 2021.
Table 2: Storage levels, Yarra basin
Catchment inflow
Catchment inflow represents the volume of water flowing into the waterways of a basin. It is calculated to be the difference between the total outflows, the known inflows, and the net change in storage volume.
Above average inflow received
Catchment inflow was 124% of the long-term average of 954,200 ML
More than the previous year
This is higher than the previous year (107% 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 now 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 .
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 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%. 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.
The annual entitlement volume is the annual diversion limit for Melbourne Water’s Yarra River, Thomson River and Silver and Wallaby Creeks bulk entitlements. The limit is calculated using a method for showing compliance with diversion limits approved by the Minister for Water in February 2018. 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 2021-22, the allocation reached 104%, higher than in the previous year when it reached 75.5%. In the Melbourne System there is no bulk entitlement or system capacity constraint that limits the allocation to 100%.
Volumes of water taken from the river systems to supply the Greater Yarra system – Thomson River Pool are reported on each individual river basin page, 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 on the water supply pages.
Table 4: Melbourne Water bulk entitlements to supply the Greater Yarra system at 30 June – Thomson River Pool
Table 5: Greater Yarra system – Thomson River Pool bulk entitlements at 30 June
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 three metropolitan water corporations — Greater Western Water (formerly City West Water), Yarra Valley Water and South East Water — hold the bulk entitlements to this desalinated seawater. These entitlements are shown in the table below.
In 2021-22, 125 GL of water was delivered from the Victorian Desalination Project, and this water was allocated to the three 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 below.
Entitlement volumes represent a maximum volume 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 varies. The rules for allocating water under an entitlement can 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 2021-22. The volume includes carryover from the previous year, seasonal allocations and net trade into the basin.
Water taken
There was 329,122 ML taken under entitlements in 2021-22, more than the year before (253,793 ML)
Restrictions on licensed diversions from unregulated rivers
Key aspects of restrictions on licensed diversions from unregulated streams in the Yarra basin in 2021-22 were:
- a total of 12 streams had bans in place at some point during 2021-22
- most of the bans were in place over summer, with a peak of 10 streams with bans in place in February 2022. This is the same as the previous year
- only three bans were remaining at the end of June 2022
- there were no restrictions on 14 streams for the whole of 2021-22.
Available water and take table
This table shows the volume of available water and the volume taken under entitlements in 2021-22.
More information on available water and take has been detailed in the How do we account for surface section on the How do we account for water page.
In 2021-22, more water was taken under entitlements than the previous year.
Table 8: Available water and take, Yarra basin
Compliance
Compliance against water entitlements is reported for this basin in three areas:
- entitlement issued: the volume of entitlements issued in a basin does not exceed formal caps, and has not increased without appropriate approvals
- water taken: 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: 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 (329,122 ML) was within the volume available for the year (495,331 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 2021-22, water for the environment in the Yarra basin comprised:
- the Yarra River Environmental Entitlement 2006, comprising 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:
- passing flow conditions on the Yarra River Environmental Entitlement 2006
- seven streamflow management plans
- 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 2021-22, a total of 26,945 ML of environmental water was delivered in the Yarra basin: 28 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) | 2020-21 (ML) |
|---|---|---|
| Melbourne Water | 491,158 | 429,339 |
