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

The Ovens system maintains a larger proportion of its natural flow regime (particularly in winter/spring) than do other regulated rivers. This is a result of relatively small storages that spill regularly and allow unregulated flows to the rivers. 

The water that flows out of the Ovens River is regulated by the largest weir pool (Lake Mulwala) 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 sites (such as Barmah Forest). 

Environmental water is held in Lake Buffalo and in Lake William Hovell and can be released under regulated conditions when the storages are not spilling. Five reaches in the Ovens system can benefit from environmental water releases. While all are important, there are relatively small environmental holdings available in the system to meet the needs of all reaches. The volume available is well short of the volume required to meet the flow objectives, but it is still delivered in the most beneficial way possible. When water is only available from the holdings, outcomes in the reaches immediately downstream of the storages are targeted. When paired with consumptive water on its way to the Murray system, additional environmental benefits are likely to be achieved in the lower Ovens River.

System map

Ovens
Grey river reaches have been included for context. The numbered reaches indicate where relevant environmental flow studies have been undertaken. Coloured reaches can receive environmental water.

Environmental watering objectives in the Ovens system

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Provide flows for native fish to move between pools and over rocky or shallow parts of the river
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Provide habitat for a wide range of waterbugs which provide energy, break down dead organic matter and support the river’s food chain
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Maintain the form of the river bank and channel plus a range of different river bed surfaces to support all stream life
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Maintain water quality for all river life
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Scour silt build-up and clean cobbles in river bed pools to maintain habitat for native plants and animals

Environmental values

The Ovens system supports many native fish species including the Murray cod, trout cod, golden perch and fly-specked hardyhead. The Buffalo River is important for large fish species during part of their breeding cycle, while trout cod are found as far up the King River as Whitfield. The Ovens system has seen a successful recovery project for trout cod, and efforts to reintroduce Macquarie perch are underway. 

Frogs (such as the giant bullfrog and growling grass frog) are abundant in the lower Ovens River and associated wetlands and in the King River upstream of Cheshunt. The lower Ovens wetlands support egrets, herons, cormorants, bitterns and treecreepers while the vegetation along the rivers is mostly river red gums, which are among the healthiest examples in north-east Victoria.

Social, cultural and economic values

Recreational activities include fishing, boating, kayaking, waterskiing, swimming and bushwalking. Irrigation supports the food and wine industries that attract tourists to the system. The lower Ovens–River Murray weir pool associated with Lake Mulwala is another tourist drawcard. There are also significant Aboriginal cultural heritage values with scar trees and artefact scatters as the physical evidence of Aboriginal people living along the river. The Ovens River continues to be a place of significance for Traditional Owners and their Nations in the system including the Yorta Yorta, Bangarang, Taungurung and Dhudhuroa peoples.

Conditions mid-2017

Wet conditions in winter/spring 2016 resulted in significant unregulated flows and the largest spring events in the Ovens catchment since 2010–11. Summer and autumn were mostly dry. A bulk drawdown of Lake Buffalo occurred in February 2017, with environmental water piggybacking to deliver a fresh event down the system. The drawdown occurred earlier than past drawdown events due to infrastructure maintenance works. 50 ML of environmental water was released from Lake William Hovell over two days in mid-March to temporarily vary the flow downstream of the storage in reach 2.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Summer/autumn fresh in reach 5 (1 fresh of 130–260 ML/day for at least 3 days in December–May)

  • Maintain flow cues to stimulate movement of native fish
  • Maintain short-term fluctuations in discharge to move sediment and maintain waterbug habitat
  • Maintain connectivity between pools and riffles
  • Scour biofilm from river bed

Supporting variability1 of summer/autumn low flows targeting reaches 1, 2 and 3

  • Maintain natural connectivity between pools and riffles
  • Maintain short-term fluctuations in discharge to move sediment and maintain waterbug habitat

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

Risk management

In preparing its seasonal watering proposal, North East CMA considered and assessed the risks of environmental watering and identified mitigation strategies. Program partners continually reassess risks and mitigation actions throughout the water year.

Engagement

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

Communities in the North East region are involved in decisions about the Ovens river system through the Ovens Environmental Water Management Plan.

Who is engaged and how

Recreational users

Recreational user groups (especially angling groups) provided advice and input to the development of the Ovens river Environmental Water Management Plan.

Environment groups

Environment groups (e.g. Landcare, Wangaratta Sustainability Group) provided advice and input to the development of the Ovens river Environmental Water Management Plan.

Members of the Wangaratta Sustainability Group support the North East Catchment Management Authority to communicate positive messages to the broader community about the benefits of environmental watering and healthy waterways.

Traditional Owners

The Dhudhuroa and Waywurru Nations were approached by Catchment Management Authority to provide input to the development of the Ovens River Environmental Water Management Plan process.

The Catchment Management Authority has an Indigenous engagement officer to assist with engagement of Traditional Owners on natural resource management.

The Dhudhuroa and Waywurru Nations are represented by the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Office and the Murray Darling Basin Authority engage Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Councils

The Alpine Shire Council and the Rural City of Wangaratta provided advice and input to the development of the Ovens river Environmental Water Management Plan.

General public

The Catchment Management Authority communicates and engages with the general public on environmental watering via their website and media releases.