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Water management in the Barmah–Millewa Forest depends on gravity distribution from the River Murray. When river flows are above 15,000 ML per day downstream of Yarrawonga Weir, both sides of the forest are managed as a whole. When flows are below this, each side of the forest can be managed separately by operating the regulators individually. Below flows of about 10,500 ML per day downstream of Yarrawonga Weir, all regulators usually remain closed.

River regulation and water extraction from the River Murray has reduced the frequency, duration and magnitude of flood events in the Barmah–Millewa Forest. This has affected the diversity, extent and condition of vegetation communities and the habitat and health of dependent animal species.

Environmental water releases seek to protect critical habitat under dry conditions and build on unregulated flows and the delivery of consumptive water en route to maximise environmental outcomes when possible. As Barmah Forest is located in the upper reaches of the River Murray, environmental water delivered to the forest can often be used again at sites further downstream as part of multi-site watering events.

System map

Murray System

Environmental watering objectives in the Barrmah Forest

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Enhance the health of river red gum communities and aquatic vegetation within the wetlands and watercourses and on the floodplain
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Protect and boost populations of native fish by providing flows to encourage fish to spawn
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Provide feeding locations and allow colonial waterbirds to successfully fledge their young
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Use flows to connect floodplains to the river, enabling carbon transfer, providing drought refuge, boosting floodplain animal and bird habitats and providing bugs and other food resources for native fish species, waterbirds, frogs and turtles
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Encourage germination and growth of Moira grass

Environmental values

The Barmah–Millewa Forest is the largest river red gum forest in Australia and the most intact freshwater floodplain system along the River Murray. The forest is a significant feeding and breeding site for waterbirds including bitterns, ibis, egrets, spoonbills and night herons, as well as for significant fish, frog and turtle populations.

The forest also supports a broad range of floodplain plants including river red gum forest, river red gum woodland, wetlands and the threatened Moira grass plains.

Social and economic values

The Barmah Forest supports a variety of recreational and tourism activities such as camping, bushwalking, fishing, river cruises and bird watching.

The forest is valued for its part in Australia's heritage and for its natural and Aboriginal and European cultural heritage values. Aboriginal sites of significance include scar trees, middens, burial sites, artefacts and ovens. The Barmah Forest continues to be a place of significance for Traditional Owners and their Nations in the region. Non-Aboriginal artefacts are largely associated with past forestry and grazing in the forest.

Conditions mid-2016

Rainfall was lower-than-average for the majority of winter-spring in 2015. A few small natural peaks above choke capacity occurred that provided water to the lower wetlands before high consumptive (household, industry and irrigation) water deliveries through the Barmah choke were combined with environmental water to provide a flood event across the floodplain from August to November.

Millewa Forest on the New South Wales side of the Murray was the primary focus of environmental water delivery in 2015–16. This was agreed as part of a reciprocal arrangement between New South Wales and Victorian program partners to maximise environmental benefits and minimise risks to the forest each year, given the constraints that restrict the ability to manage floodplain watering of both forests concurrently. Some low-level watering did occur in Barmah in 2015–16 (including shallow flooding of wetlands in late winter/early spring), in addition to some flows connecting the River Murray and the creeks through the forest. Within Barmah, environmental watering was extended through to the end of January in Boals Deadwood Wetland to support a successful colonial waterbird breeding event.

Wetland plants and river red gums responded very well to the shallow flooding in Barmah Forest. There was a clear contrast in plant health between the areas flooded and those that remained dry. The watering allowed wetland plants to reproduce and river red gums to put on a flush of new growth. Waterbirds bred successfully, with about 750 nests of ibis and 20 of royal spoonbills as well as multiple colonies of cormorants in Barmah Forest. In Millewa Forest, a similar numbers of ibis, around 200 pairs of royal spoonbills and 100 pairs of eastern great egrets also bred. About 45 male Australasian bitterns - a nationally endangered bird - were heard calling and are believed to have also bred as well as numerous other wetland-dependent bird species.

Native fish continued to be monitored but despite the watering southern pygmy perch were again not found: this has been the case since the millennium drought. While this species appears to have become locally extinct, protecting their habitat is still a high priority in case there are still remnant populations. Deliberate flow pulses in the River Murray channel through Barmah–Millewa Forest resulted in breeding of silver and golden perch. The pulses provide flow variability which is necessary to trigger perch breeding. Frogs, turtles, reptiles and other animals in the forest also benefited from the environmental water deliveries in 2015–16.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for Barmah Forest

Potential environmental watering

Environmental objectives

Spring/summer pulsed flows in the River Murray channel (3 pulses of up to 500 ML/day for 8 days each in October–December)1

  • Provide flow variability within the main river channel to encourage spawning of native fish species, primarily the golden and silver perch

Spring/summer freshes to Gulf and Boals creeks (100 ML/day for 3–5 days as required in September–March)

  • Maintain critical drought refuge areas within Barmah Forest
  • Protect fish and turtle populations in permanent waterways

Spring/summer baseflows to Gulf and Boals creeks (100 ML/day for 30–60 days as required in September–December)

  • Maintain general drought refuge areas within Barmah Forest
  • Maintain fish and turtle populations in permanent waterways
  • Maintain connectivity to the river
  • Remove accumulated organic matter (cycling carbon to the river system and minimising anoxic blackwater development)
  • Maintain water quality

Spring inundation of floodplain marshes (variable flow rates to extend the duration and inundation extent of natural flooding in September–November)2

  • Provide flooding of sufficient duration to promote growth of floodplain marsh vegetation in open plains

Targeted wetland watering to Boals Deadwood and Top Island wetlands (100–250 ML/day for 4 months in October–January)

  • Support breeding of colonial nesting and flow-dependent waterbirds

1 This action may be achieved through management of river operations and not require environmental water.

2 Environmental water is restricted to 18,000 ML per day downstream of Yarrawonga to September and 15,000 ML per day after September.

Scenario planning

Environmental water requirements vary significantly for Barmah Forest in response to natural conditions. Under drier conditions, objectives focus on maintaining the condition of permanent creeks to sustain fish and turtle populations.

As conditions become wetter, the focus shifts to the provision of larger-scale outcomes (such as extending the duration of natural flooding to promote the germination of wetland plants such as Moira grass in floodplain marshes, providing benefits to broader floodplain vegetation communities including river red gum forests).

Targeted wetland watering may occur under a range of conditions to support the breeding of colonial nesting waterbirds and other flood-dependent birds.

Table 2 Potential environmental watering for Barmah Forest under a range of planning scenarios

Planning scenario

Drought

Dry

Average

Wet

Expected river conditions

  • Unregulated flow periods unlikely
  • Flows in the River Murray will remain within channel all year
  • Some small unregulated flows in late winter/spring
  • Small chance of overbank flows in late winter/spring
  • Likely chance of small-to-medium unregulated flows in winter/spring
  • Likely chance of overbank flows in winter/spring
  • High probability of moderate-to-large unregulated flows in winter/spring
  • Expected large overbank flows

Potential environmental watering

  • Spring/summer pulsed flows in the River Murray channel
  • Spring/summer freshes
  • Spring/summer baseflows
  • Targeted wetland watering
  • Spring/summer baseflows
  • Spring inundation of floodplain marshes
  • Targeted wetland watering
  • Spring/summer baseflows
  • Spring inundation of floodplain marshes
  • Targeted wetland watering

Possible volume of environmental water required to achieve objectives1

  • 2,000 ML (no return flows)
  • 37,000 ML (no return flows)
  • 463,000 ML (with 360,000 ML return flows)2
  • 484,000 ML (with 360,000 ML return flows)2

1 The possible volumes of environmental water required in Barmah Forest are estimates; the actual volumes required are highly dependent on natural conditions.

2 The volumes identified include the volume required to achieve floodplain marsh vegetation objectives in both the Barmah and Millewa forests and may be met by unregulated flows.

Risk management

In preparing its seasonal watering proposal, the Goulburn Broken Catchment Management Authority considered and assessed risks and identified mitigating strategies relating to the implementation of environmental watering. Risks and mitigating actions are continually reassessed by program partners 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.

In the Goulburn Broken region communities are involved in decisions about the Goulburn River and wetlands, Broken River and wetlands and the Murray River and wetlands. This happens through formal advisory groups: Environmental Water Advisory Groups focusing on rivers, a wetland advisory group and the Barmah Millewa Operations Advisory Group.

Who is engaged and how

Recreational users

Through formal advisory groups, recreational users provide local advice and raise opportunities for 'shared benefits' including whether the timing of environmental watering may align with key recreational events such as cod and duck opening. Recreational users are informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Goulburn-Murray Water directly engages with recreational user groups that use Goulburn-Murray Water water storages for recreation through planned consultations and meetings to discuss storage levels and potential impacts of environmental water releases from storages.

Environment groups

Through formal advisory groups, environment groups provide local knowledge, land management advice and advocate for the environment. They are also informed of environmental water deliveries and provide data that assists with reporting on the
outcomes of environmental watering.

Landholders/farmers

Through formal advisory groups, farmers and landholders (who often own land with river frontages) provide local knowledge and land management advice. They are also informed of environmental water deliveries and provide data that assists with reporting on the outcomes of environmental watering.

Traditional Owners

Through the Goulburn Broken Catchment Management Authority Indigenous Facilitator, the Yorta Yorta Nation (responsible for managing some land and reserves in the region) is given the opportunity to provide input to seasonal watering proposals through annual briefings with the Catchment Management Authority.

There are Yorta Yorta representatives from the Goulburn Broken region who are members of the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Holder and the Murray Darling Basin Authority engage Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Councils

Through the wetland advisory group (due to their role as land managers for some wetlands), Councils provide local advice.
They also support local advertising during water delivery and share data for reporting.

Goulburn-Murray Water consults with the Greater Shepparton City Council and the Moira Shire Council regularly on water management, including on environmental water management.

General public

The Goulburn Broken Catchment Management Authority communicates through their website, media releases, advertisements in local papers, a column in Country News, in the Goulburn Broken Catchment Management Authority bi-monthly newsletter, social media, radio, community forums and partnered research.