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As its storages are quite small and spill regularly, the Ovens system maintains a large proportion of its natural flow regime, particularly in winter/spring. However, the storages and licensed water extractions throughout the system can restrict flow during low flow periods, and parts of the system can become quite flow stressed during summer and autumn.

The Ovens River flows into Lake Mulwala on the Murray River, the largest weir pool on the Murray regulated system. Ovens River flows contribute to the reliability and variability of flows in the Murray River and support many downstream uses including irrigation, urban supply and watering of iconic floodplain sites (such as Barmah Forest).

Water for the environment is held in Lake Buffalo and in Lake William Hovell and can be released when the storages are not spilling. Five reaches in the Ovens system can benefit from releases of water for the environment. While all are important, there is a relatively small volume (123 ML) of water available, and it is insufficient to meet most of the environmental flow objectives. The available water is used selectively to deliver the greatest possible environmental benefit. Water for the environment is most commonly used in the Ovens system to deliver critical flow events in reaches immediately below the two main storages, or it is used in conjunction with operational water  releases to influence flow in the lower Ovens River. It is also used to fill and top up Mullinmur Wetland in Wangaratta.

Traditional Owners
Storage manager

System map

Environmental watering objectives in the Ovens system

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Maintain the size and distribution of native fish populations
Landscape icon
Maintain the form of the riverbank and channel and ensure river bed surfaces are in suitable condition to support all stream life
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Maintain the condition and extent of wetland vegetation communities
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Maintain an adequate abundance and diversity of waterbugs, to support river food webs and associated ecosystem processes
Water icon
Maintain water quality for all river life

Environmental values

The diverse aquatic habitat and abundant food resources associated with the Ovens system support a wide range of native fish species including Murray cod, trout cod, golden perch and unspecked hardyhead. The Buffalo River provides valuable habitat for large-bodied fish species during part of their breeding cycle, while trout cod have a large range within the system and are found as far up the King River as Whitfield. A project to recover trout cod populations in the Ovens system has been successful, and efforts to reintroduce Macquarie perch are continuing.

Frogs (such as the giant banjo frog and growling grass frog)are abundant in the lower reaches and associated wetlands of the Ovens River and in the King River above Cheshunt. The lower Ovens wetland complex contains over 1,800 wetlands, is listed as nationally significant and is home to a variety of waterbirds including egrets, herons, cormorants and bitterns. The streamside zones of river channels throughout the Ovens system support some of Victoria’s healthiest river red gum forests and woodlands, while the wetlands support a variety of aquatic and semi-aquaticvegetation communities.

Water for the environment was delivered to Mullinmur Wetland at Wangaratta for the first time in 2019–20. This site has been the focus of several environmental improvement projects in recent years. Specific management actions include carp removal, a revegetation program and a project that started in December 2019 to determine whether the wetland can support a sustainable brood stock population of native freshwater catfish. The Arthur Rylah Institute translocated 60 freshwater catfish into Mullinmur Wetland in December 2019, and ongoing monitoring throughout 2020–21 will assess the viability of the population.

Recent conditions

Hot, dry conditions prevailed throughout much of the Ovens River catchment in 2019–20, resulting in flows into  Lake Buffalo and Lake William Hovel being well below the longterm average until rainfall began filling storages in  March 2020. Water for the environment held in Lake Buffalo was used in conjunction with an operational bulk water  transfer to deliver a small autumn fresh in the Buffalo River in early March. Small increases in river height  were also observed in reach 4 of the Ovens River during this fresh. Water for the environment was delivered in  conjunction with water held by the Taungurung Land and Waters Council from Lake William Hovell in late March,  providing flow variability to reaches 3 and 4 of the King River.

Bushfires burnt large areas of the catchment above Lake Buffalo during summer, and subsequent heavy rainfall  washed ash and other sediment into upstream tributaries, causing poor water quality on occasions in the Buffalo  and Ovens rivers. Natural events, operational deliveries and the use of water for the environment helped flush  deposited ash and sediments and improve water quality.

Water for the environment was delivered to Mullinmur Wetland at Wangaratta for the first time in December 2019,  to prepare habitat for translocated freshwater catfish. A second top-up was delivered in February 2020, to  maintain water levels to support the growth and recruitment of aquatic vegetation and sustain the translocated fish.

Traditional Owner cultural values and uses

North East CMA has consulted with Taungurung Land and Waters Council and Yorta Yorta Nation Aboriginal Corporation in environmental water planning for the Ovens system. The environmental and ecological objectives of the proposals were supported and align with the broad values of these Traditional Owner groups. 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.

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

Taungurung Land and Waters Council may consider using their water entitlement in the King River system to support environmental objectives as part of their goal of healing Country. Taungurung Land and Waters Council’s 39 ML of allocation has been released from Lake William Hovell twice previously as an environmental flow in partnership with North East CMA, Goulburn-Murray Water and the VEWH to provide additional water to the King River and assist in healing Country. The flow provided a small variation within the water level to inundate new habitat for instream biota (fish and macroinvertebrates), allowing them to move more freely and find new sources of food.

Social, recreational and economic values and uses

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

  • water-based recreation (such as boating and fishing)
  • riverside recreation and amenity (such as camping)
  • community events and tourism (such as providing a setting for community gatherings and sporting events, and citizen science projects)
  • socio-economic benefits (such as businesses used by anglers).

If the timing or management of planned environmental flows may be modified to align with a community benefit, this is acknowledged in Table 1 with an icon.

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Watering planned to support angling activities

Environmental water will be used to top up Mullinmur Wetland over summer, support aquatic vegetation and support native catfish which were translocated to the wetland in 2019 from a drying lake in Barham, New South Wales. This will enable the site to be used as a catfish broodstock location for future reintroductions into the region.

The water will also support other benefits for the local community, as the site is managed by the Catholic Education Department with support from Wangaratta Landcare and Sustainability Incorporated. It is used as a community and environmental educational site for Galen Catholic College students, young people attending the Borinya Wangaratta Community Partnership and other members of the local community, demonstrating the important ecological functions that wetlands provide and how water for the environment is used to support ecological values.

Scope of environmental watering

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

Potential environmental
watering action

Functional watering objective Environmental

Environmental objective

Autumn fresh (one fresh of greater than 430 ML/day for three days in reaches 1 and 4, and greater than 130-260 ML/day in reach 5 during March to April)

  • Provide flow cues to stimulate the movement of native fish
  • Maintain connectivity between pools for fish movement
  • Mix pools to improve the water quality
  • Provide small variations in river levels and velocity, to flush sediment from hard substrates and maintain waterbug habitat
  • Scour biofilm from the river bed
Fish iconMountain iconsInsect iconWater drop icon

Summer/autumn low-flow variability (greater than 80 ML/day for one to two days during February to March in reaches 1, 2 and 3)

Billabong icon

  • Maintain connectivity between pools for fish movement and water quality
  • Provide small variations in river levels to move sediment and maintain waterbug habitat

Fish iconInsect iconWater drop icon

Mullinmur Wetland (topup during November to February)

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  • Maintain the water level to support the growth and recruitment of aquatic vegetation
  • Maintain habitat for freshwater catfish

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Engagement

Table 2 shows the partners with which North East CMA engaged when preparing the Ovens 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 North East Regional Catchment Strategy and North East  Waterway Strategy.

Table 2 Partners engaged in developing the Ovens system seasonal watering proposal

Partner engagement
  • Wangaratta Landcare and Sustainability Incorporated
  • Commonwealth Environmental Water Office
  • Goulburn-Murray Water
  • City of Wangaratta
  • Victorian Fisheries Authority
  • Catholic Education Department – Sandhurst Diocese
  • Arthur Rylah Institute (Department of Environment, Land, Water and Planning)
  • Yorta Yorta Nation Aboriginal Corporation
  • Taungurung Land & Waters Council

Page last updated: 24/07/20