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Up to 400,000 ML per year (long-term average diversion limit) can be harvested from the Yarra River system for consumptive use in Melbourne and surrounding areas. The Upper Yarra, O’Shannassy and Maroondah reservoirs harvest water from headwater tributaries, and a pump station at Yering is used to divert water from the Yarra River to Sugarloaf Reservoir.

Flow in the upper reaches of the Yarra River is influenced by tributaries (such as Armstrong Creek, McMahons Creek, Starvation Creek, Woori Yallock Creek, Watts River and Little Yarra River). Urbanised tributaries (such as Olinda Creek, Mullum Mullum Creek, Diamond Creek, Plenty River and Merri Creek) provide additional water to the middle and lower reaches of the Yarra River. Environmental flows can be released from the Upper Yarra, Maroondah and O’Shannassy reservoirs to support ecological processes and environmental outcomes in downstream river reaches and wetlands. The priority environmental flow reaches in the Yarra River are reaches 2 and 5, shown in the system map below. Water for the environment that is delivered to reaches 2 and 5 will help meet flow targets in downstream reaches.

Plenty River rises from the slopes of Mt Disappointment in the Great Dividing Range about 50 km north of Melbourne. It flows downstream through rural and semi-rural areas and Plenty Gorge before joining the Yarra River near Viewbank, east of Banyule Flats Reserve. Yan Yean Reservoir is located off the waterway, north of Plenty Gorge, and it receives flows from Toorourrong Reservoir via a channel. The Plenty River has not received managed environmental flows before, but there may be opportunities to deliver water for the environment from Yan Yean Reservoir from 2020–21 onwards.

Waterway manager
Traditional Owners
Storage manager
Environmental water holder

System map

Environmental watering objectives in the Yarra River

Fish icon
Protect and increase populations of native fish including threatened species (such as the Australian grayling, Macquarie perch and river blackfish)
Frog icon
Maintain the population of frogs, particularly on the mid-Yarra floodplain
Landscape icon
Maintain the form of the river channel Scour silt from riffles and clean cobbles
Platypus icon
Maintain the population of resident platypus
Plant icon
Increase, strengthen and maintain native streamside and aquatic vegetation on the riverbank and in the channels

Increase, strengthen and maintain the growth of threatened wetland plant species to rehabilitate shallow marsh, deep marsh and freshwater meadows on the floodplain and billabongs
Insect icon
Protect and increase communities of waterbugs, which break down dead organic matter and support the river’s food chain
Water icon
Improve water quality in river pools, ensuring adequate oxygen concentration in the water to support fish, crustaceans and waterbugs

Environmental values

The upper Yarra River (reaches 1–3) provides habitat for a range of native fish species including river blackfish, mountain galaxias and common galaxias, and has goodquality streamside and aquatic vegetation. The middle and lower Yarra River (reaches 4–6) flows through forested gorges, cleared floodplains and some highly- urbanised areas, and supports several populations of native fish including Australian grayling, river blackfish, Macquarie perch and tupong. Macquarie perch was introduced to the Yarra River last century, and the population is now considered one of the largest and most important in Victoria.

The Plenty River (reach 9) provides habitat for waterbug populations and native fish species (such as common galaxias and river blackfish). Platypus have been detected in the Plenty River in the past, but none have been recorded in recent surveys.

Billabongs are an important feature of the Yarra River floodplain between Millgrove and Yering Gorge and in the lower reaches around Banyule Flats near Heidelberg. The billabongs support distinct vegetation communities and provide foraging and breeding habitat for waterbirds and frogs. Except in very high flows, most billabongs are disconnected from the Yarra River.

Recent conditions

Rainfall in 2019–20 in the Yarra catchment was above the long-term average, and tributary inflows significantly contributed to flow in the Yarra and Plenty rivers throughout the year. O’Shannassy Reservoir was offline for most of the year for maintenance, so most flow in the O’Shannassy River passed directly into the Yarra River.

Natural rainfall events, combined with the larger-thannormal inflows from the O’Shannassy River, achieved most of the high-priority planned watering actions for 2019–20, and some lower-priority watering actions (such as winter/ spring freshes) provided important flow variability. One of the highest-priority planned watering actions for the Yarra River was an autumn high flow to support the migration and spawning of Australian grayling. The planned environmental flow release in April 2020 coincided with a natural rain event, which reduced the volume of environmental water needed to achieve the target flow.

In September 2019, water for the environment was used to partially fill Banyule Billabong on the lower Yarra floodplain near Heidelberg for the first time since 2016–17. Monitoring by Melbourne Water indicated that the watering action drowned some of the terrestrial plants that had colonised the bed of the wetland in recent years and stimulated growth of some native wetland plant species. Water for the environment was used to fill Yering Backswamp in May 2020, to maintain water- dependent vegetation and aquatic animals.

Traditional Owner cultural values and uses

Wurundjeri Woi-Wurrung Cultural Heritage Aboriginal Corporation and Melbourne Water are working towards an integrated approach that includes Wurundjeri as active participants in the planning, delivery, and monitoring of all works on the lower Yarra floodplain. Melbourne Water has also made initial contact with Bunurong Land Council Aboriginal Corporation and Boon Wurrung Foundation to discuss environmental watering along the lower Yarra River.

Waterway managers are seeking opportunities to increase the involvement of Traditional Owners in environmental water planning and management. Where Traditional Owners are more deeply involved in the planning and/or delivery of environmental flows for a particular site, their contribution is acknowledged in Table 1 with an icon.

Billabong icon

Watering planned and/or delivered in partnership with Traditional Owners to support Aboriginal cultural values and uses

In 2019 Wurundjeri Woi-Wurrung Cultural Heritage Aboriginal Corporation completed the Bulleen‐ Banyule Flats Cultural Values Study, which details places of Traditional Owner tangible and intangible significance. Melbourne Water has supported this project by attending on-Country visits with Elders and hope to link this study and the identified potential cultural benefits with environmental watering.

Wurundjeri Woi-Wurrung Cultural Heritage Aboriginal Corporation’s Water Unit engaged the Narrap team to undertake on-ground activities, such as water quality and frog monitoring, through the cultural water program at billabong sites along the lower Yarra floodplain. Monitoring is underway at Banyule Billabong following a delivery of water for the environment in 2019–20 and similar work will likely be undertaken at Annulus Billabong in 2020–21.

Social, recreational and economic values and uses

In planning the potential watering actions in Table 1, Melbourne Water considered how environmental flows could support values and uses including:

  • water-based recreation (such as kayaking, canoeing, fishing and swimming)
  • riverside recreation and amenity (such as walking, running, cycling, camping and birdwatching)
  • community events and tourism (such as the Moomba Festival and the Inflatable Regatta)
  • socio-economic benefits (such as diverters for irrigation, domestic and stock uses, and Melbourne’s water supply).

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Yarra system

Potential environmental watering action Functional watering objective Environmental objective

Summer/autumn low flow (80–200 ML/day during December to May)

  • Physically mix pools to minimise the risk of stratification and low oxygen
  • Maintain access to habitats for fish, waterbugs and platypus
Fish iconPlatypus iconInsect iconWater drop icon

Winter/spring low flow (200–350 ML/day during June to November)

  • Physically mix pools to minimise the risk of stratification and low oxygen
  • Maintain access to habitats for fish, waterbugs and platypus
  • Wet bank vegetation to promote growth

Fish iconPlatypus iconPlant iconInsect icon
Water drop icon

Summer/autumn fresh (one to three freshes of 350–750 ML/day for two to four days during December to May)

  • Flush pools to prevent a decline in water quality
  • Scour sediment and biofilm from gravel in riffles and pools to maintain habitat quality for fish and waterbugs
  • Provide opportunities for localised movement of fish and platypus
  • Wet the banks of the river to maintain flood-tolerant vegetation on the banks

Fish iconMountain iconsPlatypus iconPlant iconInsect iconWater drop icon

Autumn high flow (one fresh of 560–1,300 ML/day for seven to 14 days during April to May)

  • Cue the migration of Australian grayling
  • Scour sediment and biofilm from gravel in riffles and pools to maintain habitat quality for fish and waterbugs

Fish iconMountain icons

Winter/spring fresh (one to two freshes of 700–2,500 ML/day for three to seven days during June to November)

  • Scour sediment and biofilm from gravel in riffles to improve spawning opportunities for Macquarie perch
  • Wet native streamside vegetation on the banks of the river to promote growth
  • Provide cues for upstream migration of juvenile migratory fish (e.g. Australian grayling and tupong)

Fish iconMountain iconsPlant icon

Spring high flow (one high flow of 700–2,500 ML/day for 14 days in September)

  • Scour sediment and biofilm from gravel in riffles
  • Provide prolonged wetting to favour flood-tolerant native vegetation in the streamside zone
  • Provide cues for upstream migration of juvenile migratory fish (e.g. Australian grayling and tupong)
  • Promote spawning of Macquarie perch

Fish iconMountain iconsPlant icon

Plenty River

Winter/spring low flow (20 ML/day during June to November)

  • Physically mix pools to minimise the risk of stratification and low oxygen
  • Maintain access to habitats for fish and waterbugs
  • Wet bank vegetation to promote growth

Fish iconPlant iconInsect iconWater drop icon

Winter/spring freshes (four freshes of 70 ML/day for three days during June to November)

  • Scour sediment and biofilm from gravel in riffles
  • Provide access to habitats for fish and waterbugs
  • Wet native streamside vegetation on the banks of the river to promote growth

Fish iconPlant iconInsect iconWater drop icon

Billabong watering

Annulus Billabong (partial fill in winter/spring)

Billabong icon

  • Prime wetland for a fill
  • Wet the wetland bed for up to three months to support the growth of threatened wetland plant species to rehabilitate shallow marsh, deep marsh and freshwater meadows
  • Provide habitat for frogs, waterbugs and eels
Fish iconFrog iconPlant iconInsect icon

Yering Backswamp (partial or complete fill in autumn and winter/spring)

  • Wet the deepest parts of the wetland to about 80 cm to provide habitat for fish, frogs and waterbugs
  • Wet remaining areas of wetland to about 40–60 cm to support the growth of threatened wetland plant species and encourage the regeneration of spreading aquatic herbs
Fish iconFrog iconPlant iconInsect icon

Engagement

Table 2 shows the partners and stakeholder organisations with which Melbourne Water engaged when preparing the Yarra system seasonal watering proposal.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the Port Phillip and Western Port Regional Catchment Strategy and Melbourne Water's Healthy Waterways Strategy.

Table 2 Partners and stakeholders engaged in developing the Yarra system seasonal watering proposal

Partner and stakeholder engagement
  • Environment Victoria
  • Native Fish Australia
  • Yarra River Keeper
  • Banyule City Council
  • Boroondara City Council
  • Department of Environment, Land, Water and Planning | Water and Catchments
  • Manningham City Council
  • Melbourne Water Service Delivery
  • Parks Victoria
  • Environment Protection Authority
  • Port Phillip and Westernport Catchment Management Authority
  • Nillumbik City Council
  • Yarra Ranges Shire Council
  • Individual landholders
  • Licensed diverters
  • Warburton Holiday Park
  • Paddle Victoria
  • VRFish
  • Whitehorse Canoe Club
  • Melbourne University – research collaborators
  • Monash University
  • Arthur Rylah Institute (Department of Environment, Land, Water and Planning)
  • Wurundjeri Woi-Wurrung Cultural Heritage Aboriginal Corporation
  • Boon Wurrung Foundation
  • Bunurong Land Council Aboriginal Corporation

Page last updated: 24/07/20