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The Latrobe River originates on the Mount Baw Baw Plateau and flows into Lake Wellington, the westernmost point of the Gippsland Lakes. The upper Latrobe River is relatively intact, but the lower Latrobe River that flows through the Latrobe Valley is degraded due to historic river management practices. Most snags have been removed from the river and many sections have been artificially straightened. This reduces the diversity of habitat that aquatic plants and animals depend on.

Environmental water is supplied from Blue Rock Reservoir on the Tanjil River. The reservoir also supplies water for other entitlement holders (such as the electricity generators in the Latrobe Valley).

The Latrobe River from Rosedale to the Thomson River confluence (reach 5 – see below) is the priority for environmental watering because it contains endangered plant communities that have good potential for recovery. With an appropriate water regime it is possible to improve the quality of riparian vegetation. This in turn stabilises the river banks and provides improved habitat that has been lost due to historic efforts to straighten the channel and remove snags.

Storage manager
Environmental water holder

Environmental watering objectives in the Latrobe River

Fish icon
Improve habitat for native fish including black bream and estuary perch
Landscape icon
Enable formation of in-stream bars to help stabilise the structure and condition of the river channel. This will help to reduce the load of sediment and nutrients flowing into the Gippsland Lakes
Plant icon
Establish native plants on bars and lower parts of the banks to stabilise the river channel

System map

Latrobe River and Wetland System
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 values

The Latrobe River contains estuarine and freshwater fish species including the black bream, Australian bass, grayling and short- and long-finned eel. Along the banks in the lower reaches there are intact stands of swamp scrub, an endangered vegetation type that is characterised by dense stands of swamp paperbark and tea tree. The upstream reaches contain some continuous stands of river red gums and a tall shrub layer. Mature river red gums are also adjacent to the lower Latrobe wetlands and provide nesting habitat for birds of prey (such as sea eagles) that hunt in the wetlands.

Social and economic values

The Latrobe Valley is the centre of Victoria's energy industry and water from the Latrobe River is essential for electricity generation. The lower Latrobe River is commercially fished for eel and carp. It  also contains black bream and estuary perch, which are favoured by recreational fishers. The waterways in the Latrobe system hold significance for Traditional Owners. Waterways and wetlands in the region are important ceremonial places and for thousands of years the Latrobe River has provided resources such as food and materials to the Gunaikurnai people.

Conditions mid-2016

Rainfall for the Latrobe River catchment was lower than average in 2015–16, mostly due to a particularly dry spring. Although winter and spring were relatively dry, Blue Rock Reservoir was full at the start of the water year and spills occurred in winter and spring. The largest flow occurred in September 2015 and this caused minor flooding of the lower Latrobe River.

An autumn fresh (small pulses of water) of 1,300 ML per day was delivered from Blue Rock Reservoir in April and May 2015. The water was delivered to improve vegetation condition and channel structure in the Latrobe River, and to improve water quality by flushing a salt wedge that forms in the lower Latrobe in summer and autumn when flows are low.

An exciting finding from 2014–15 was the capture of Australian grayling eggs during an environmental water release in autumn. The eggs were found in a bend in the river that had been restored to its more natural shape. The West Gippsland Catchment Management Authority has restored several meander bends in the Latrobe River which had flow diverted due to historical channel straightening and widening. The meander where the eggs were found has a gravel river bed, which is favourable habitat for Australian grayling spawning that has been degraded in most of the Latrobe River.

The environmental water was not intended for Australian grayling spawning and further research is required to determine the significance of the finding and to inform future environmental recommendations for the Latrobe River.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the Latrobe River

Potential environmental watering

Environmental objectives

Spring/summer freshes (1,300 ML/day for 2–4 days in September–February)

  • Improve vegetation diversity, condition and abundance along lower banks and increase recruitment of in-stream vegetation

Autumn/winter freshes (1,300 ML/day for 2–4 days in March–August)

Winter/spring baseflows (690–1,500 ML/day from June–November)

  • Facilitate the formation of in-stream bars (elevated deposits of sediment and gravel in the river channel)

Summer/autumn baseflows (up to 690 ML/day from December–May)

  • Provide in-stream habitat for aquatic biota (especially waterbugs, fish and vegetation)

Scenario planning

The long-term aim for the Latrobe River is to rehabilitate vegetation and improve the channel structure. Spring freshes are very important to achieve these objectives: they improve the growth of riparian vegetation which stabilises banks and increases habitat.

Climate and rainfall from July to November is therefore an important consideration in deciding when to use environmental water to meet vegetation objectives. In a dry year there is likely to be low natural achievement of spring and early summer freshes, so environmental water will be delivered to supplement flows, to achieve the desired flow rates for riparian vegetation.

If good inflows occur in winter and spring, Blue Rock Reservoir will spill and most spring priorities will be delivered naturally. If natural flows occur then environmental water will not be needed for spring releases and water can be reserved for use in late summer and autumn.

Table 2 Potential environmental watering for the Latrobe River under a range of planning scenarios

Planning scenario

Drought

Dry

Average

Wet

Expected river conditions

  • Small contributions from unregulated reaches and tributaries of the Latrobe River with little opportunity for freshes to occur naturally
  • Consumptive demand from Blue Rock Reservoir will be very high and regular releases to the Tanjil River will contribute substantially to baseflows
  • There will be some unregulated flows that contribute to baseflows and freshes, but extended periods of high flows will be absent and freshes will be infrequent
  • Consumptive demand from Blue Rock Reservoir will be high and contribute to baseflows
  • Unregulated flows will provide baseflows and multiple freshes, most likely in winter and spring
  • A moderate amount of spills are likely and there will be releases for consumptive users which will partially contribute to baseflows
  • Multiple spills from Blue Rock Reservoir will provide extended durations of high flows and overbank flows
  • No significant releases from consumptive entitlements in Blue Rock Reservoir are likely

Expected availability of environmental water

  • 16,200 ML
  • 18,200 ML
  • 18,700–23,200 ML
  • 18,700–31,200 ML

Potential environmental watering

  • 1 spring/summer fresh
  • 1 autumn/winter fresh
  • Winter/spring baseflows
  • Up to 3 spring/summer freshes
  • Up to 2 autumn/winter freshes
  • Winter/spring baseflows
  • Summer/autumn baseflows
  • Up to 3 spring/summer freshes
  • Up to 2 autumn/winter freshes
  • Winter/spring baseflows
  • Summer/autumn baseflows
  • Up to 4 spring/summer freshes
  • Up to 4 autumn/winter freshes
  • Winter/spring baseflows
  • Summer/autumn baseflows

Possible volume of environmental water required to achieve objectives

  • 12,300 ML
11,200 ML
  • 15,900 ML
  • 0–11,000 ML

Risk management

In preparing its seasonal watering proposal, West Gippsland Catchment Management Authority considered and assessed risks, and identified mitigating strategies, relating to implementing 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 West Gippsland region communities are involved in decisions about the Thomson and Macalister river systems and the Lower Latrobe wetlands. The community is engaged informally and through the Macalister river Project Advisory Group.

Who is engaged and how

Recreational users

A representative of VRFish sits on the Macalister river Project Advisory Group.

West Gippsland Catchment Management Authority engages with Field & Game Australia when developing the Lower Latrobe wetlands seasonal watering proposal (annual scoping). Field & Game Australia shares wetland bird count data with the Catchment Management Authority which helps with reporting on environmental watering outcomes.

The Catchment Management Authority notifies many recreational user groups about environmental water deliveries. These groups include canoe clubs, outdoor education companies and school groups (many of whom come from outside of the region). These groups are interested in managing safety and also achieving opportunities for shared benefits from environmental watering (e.g. kayaking on higher flows in the Thomson river).

Environment groups

Representatives from environment groups (Environment Victoria, Landcare and Native Fish Australia) sit on the Macalister river Project Advisory Group.

Irrigators/farmers

Irrigation representatives sit on the Macalister river Macalister river Project Advisory Group.

Southern Rural Water sends environmental water delivery notifications to their irrigation customers on behalf of the Catchment Management Authority. These irrigation customers are often primarily interested in environmental watering from a safety and infrastructure protection perspective.

Traditional owners

Through the Catchment Management Authority Indigenous facilitator, the Gunaikurnai Land and Waters Aboriginal Corporation has been invited to join the Macalister river Project Advisory Group.

The Catchment Management Authority and Gunaikurnai Land and Waters Aboriginal Corporation have a Memorandum of Understanding. The Catchment Management Authority recognises the recently developed Gunaikurnai Land and Waters Aboriginal Corporation draft Whole Of Country Plan which contains aspirations for rivers and wetlands in Gippsland.

Councils

The Wellington Shire Council is a member of the Macalister river Macalister river Project Advisory Group.

The Wellington Shire Council, the Latrobe City Council and the Baw Baw Shire Council are all on the Southern Rural Water environmental water delivery notification list.

General public

Public signage informing the general public about upcoming environmental water deliveries is set up a few days before a planned delivery along key recreational sites in the upper Thomson River. This is for primarily for public safety purposes.