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The Ovens River rises in the steep, forested mountains of the Great Dividing Range near Mount Hotham and flows about 150 km to join the River Murray in the backwaters of Lake Mulwala. The system contains two small water storages: Lake Buffalo on the Buffalo River and Lake William Hovell on the King River. The regulated reaches of the Ovens system include the Buffalo and King rivers downstream of these storages and the Ovens River from its confluence with the Buffalo River to the River Murray.

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 River Murray, the largest weir pool on the Murray regulated system. Ovens River flows contribute to the reliability and variability of the flow regime for the River Murray 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 well-short of the volume required to meet all environmental flow objectives. The available water is used selectively to deliver the greatest possible environmental benefit. Water for the environment is mostcommonly used in the Ovens system to deliver critical flow events in reaches immediately downstream of the two main storages, or it is used in conjunction with operational water releases to influence flow in the lower Ovens River.

System map

Environmental watering objectives in the Ovens system

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

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 upstream of 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 riparian 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 semiaquatic vegetation communities.

The first trial delivery of water for the environment to a wetland on the Ovens floodplain is proposed for 2019–20. The target site is Mullinmur Wetland at Wangaratta, which 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 is currently underway to determine whether the wetland can support a sustainable brood stock population of native freshwater catfish. Brood stock are important for catfish recovery (reintroduction) projects.

Recent conditions

A warm and dry 2018–19 resulted in relatively low flows throughout the Ovens system. Inflows into the storages were well-below average, although both Lake William Hovell and Lake Buffalo filled. The bulk transfer of water from Lake Buffalo to the Murray that normally occurs in autumn did not proceed in 2018–19, so water for the environment was used to briefly increase low flows below the storages in autumn. These flows helped to connect habitats within the channel that can become isolated during low-flow periods, and they also improved water quality.

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 low-flow fresh in reaches 1, 4 and 5: one fresh of ≥ 430 ML/day for three days in reaches 1 and 4, > 130–260 ML/day in reach 5 (March/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 icons Insect iconWater drop icon

Summer/autumn low-flow variability1 in reaches 1, 2 and 3

  • 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 (top-up during November to February)
  • Maintain the water level to support the growth and recruitment of
    aquatic vegetation
  • Maintain habitat for native catfish

Fish iconPlant icon

1 Operational releases from storage can vary, with water for the environment used to provide some variability over one or two days.

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 Sustainability Network
  • Arthur Rylah Institute
  • Victorian Fisheries Authority
  • Catholic Education Department – Sandhurst Diocese
  • Rural City of Wangaratta
  • Commonwealth Environmental Water Office
  • Goulburn-Murray Water
  • Victorian Environmental Water Holder
  • Taungurung Land and Waters Council
  • Yorta Yorta Nation Aboriginal Corporation