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The lower Latrobe wetlands are Sale Common, Dowd Morass and Heart Morass. The wetlands are on the floodplain of the Latrobe River between its confluence with the Thomson River and Lake Wellington.

River regulation and water extraction from the Latrobe, Thomson and Macalister rivers has reduced the frequency of small- and medium-sized floods that naturally inundate the wetlands. This problem is worsened by saline water intrusion into Dowd Morass and Heart Morass from Lake Wellington. Construction of levees and drains and the filling in of natural depressions have also altered water movement in and through the wetlands. However, the drainage and flooding regime in all three wetlands can be managed to some extent through the use of regulators connected to the Latrobe River.

Storage manager
Environmental water holder

Environmental watering objectives in the Latrobe wetlands

bird icon
Provide habitat for waterbirds
Fish icon
Control carp abundance, particularly at Sale Common and Dowd Morass
Plant icon
Promote dispersal and germination of wetland plants

Environmental values

The Latrobe River provides a large source of freshwater to the Gippsland Lakes Ramsar site, of which the lower Latrobe wetlands are an important component. The lower Latrobe wetlands (Dowd Morass, Heart Morass and Sale Common) provide a variety of habitats that suit a range of different birds at different times. For example, colonial waterbirds (such as royal spoonbill and straw-necked and Australian white ibis) find breeding habitat among swamp paperbark trees in spring. Over summer during a drying phase, the mudflats provide feeding habitat for migratory shorebirds (such as sandpipers). Open water is important year-round for waterfowl and fish-eating birds (such as egrets).

In recent years, rare and threatened species (such as the freckled duck and green and golden bell frog) have been found at Heart Morass.

Social and economic values

Sale Common is a state game refuge located close to the town of Sale that provides an excellent opportunity to observe native plants and animals. Dowd Morass is a state game reserve commonly used by hunters, and Heart Morass consists of mostly private landholdings and is also used by hunters. An appropriate water regime in the lower Latrobe wetlands increases waterbird abundance and provide opportunities for bird watching and hunting when the wetlands are in a wet phase.

The lower Latrobe wetlands hold significance for Traditional Owners. Waterways and wetlands in the region are important ceremonial places and for thousands of years the lower Latrobe wetlands have provided resources such as food and materials to the Gunaikurnai people.

Conditions mid-2016

Natural flows to the wetlands were infrequent and small-scale in 2015–16. This resulted in a substantial drawdown of Sale Common and Heart Morass. A partial drawdown of Dowd Morass also occurred, but the extent of the drying was tempered by a small unregulated flow to Dowd Morass in September 2015.

The widespread drying was welcome because in previous years the Latrobe wetlands were continuously inundated, and only partial drawdowns occurred each summer. The drying improved vegetation diversity by allowing plants to germinate on exposed mudflats. It also provided some control of carp.

Waterfowl counts in autumn were lower than in previous years. This was partially attributable to the wetland drying that occurred. It was also a consequence of dryer conditions across all of south-east Australia, meaning that waterfowl were less abundant than usual.

An autumn wetting flow was delivered to Heart Morass in March to June 2016 to provide seed dispersal and support opportunities for waterbirds. This was the first time that water has been actively delivered to Heart Morass using the environmental entitlement for the Latrobe wetlands.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for the lower Latrobe wetlands

Potential environmental watering

Environmental objectives

Sale Common

Partial, substantial or complete drawdown (primarily August–March)

  • Promote oxygenation of surface soils, breakdown of accumulated organic matter and nutrient recycling
  • Encourage the growth and reproduction of wetland plants across the wetland bed
  • Reduce the number and size of European carp

Wetting flow (February–May)

  • Provide feeding and sheltering habitat for wetland animals, particularly waterbirds and frogs
  • Discourage the spread of giant rush

Partial wetting flow (August–November)

  • Encourage the growth and reproduction of wetland plants, particularly tall marsh, aquatic herbland and aquatic sedgeland
  • Provide feeding and breeding habitat for wetland animals, particularly waterbirds and frogs

Wetting flow (anytime)

  • Mimic the natural inundation regime
  • Control invasive vegetation

Dowd Morass and Heart Morass

Partial drawdown (primarily August–March)

  • Promote oxygenation of surface soils, breakdown of accumulated organic matter and nutrient recycling
  • Encourage the growth and reproduction of wetland plants, particularly swamp shrub, tall marsh, aquatic herbland and brackish herbland
  • Reduce the number and size of European carp

Wetting flow (February–May)

  • Provide feeding habitat for wetland animals, particularly waterbirds

Wetting flow (anytime)

  • Avoid/mitigate risks to wetland plants and waterbird habitat from adverse salinity and exposure of acid sulphate sediment
  • Mimic the natural inundation regime

Partial wetting flow (August–November)

  • Encourage colonial waterbird breeding
  • Reduce salinity
  • Encourage the growth and reproduction of wetland plants, particularly swamp scrub, tall marsh, aquatic herbland and brackish herbland
  • Provide feeding and breeding habitat for wetland animals, particularly waterbirds and frogs

Scenario planning

Natural flows are very influential in the Latrobe wetlands. In a drought and dry year, extensive drawdowns will occur in all three wetlands. Partial drawdowns will occur in an average year, but if conditions are wet the ability to manage drawdown is diminished, and uncontrolled flows will provide widespread inundation throughout the year.

The approach in 2016–17 is to allow water levels to fluctuate according to natural seasonal conditions. At times some selective small-scale flooding and drainage may be managed to amplify the natural conditions and improve environmental outcomes. Short-duration wetting flows may be delivered at any time when water is needed to mitigate risks of salinity and acid sulphate soils or to provide habitat for waterbirds.

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

Planning scenario

Drought

Dry

Average

Wet

Expected catchment conditions

  • No natural flows from the Latrobe River
  • Wetlands are likely to dry completely
  • Moderate winter and spring flows and flushing flows
  • Wetlands could be filled or partially filled with a minor drawdown in summer
  • Major flows in winter/spring and possibly autumn/winter
  • Wetlands will be filled naturally with very little drawdown over summer

Sale Common

Potential environmental watering

  • Complete drawdown (July–June)
  • Wetting flows (anytime)
  • Substantial drawdown (August–April)
  • Wetting flows (anytime)
  • Wetting flows (February–May)
  • Wetting flows (August–November)
  • Partial drawdown (August–March)
  • Wetting flows (anytime)
  • Wetting flows (February–May)
  • Flushing/wetting flows (August–November)
  • Partial drawdown (December–March)
  • Wetting flows (February–May)
  • Wetting flows (anytime)

Possible volume of environmental water required to achieve objectives

0–1,300 ML

0–1,300 ML

0–1,300 ML

0 ML

Dowd Morass

Potential watering actions

  • Complete drawdown (July–June)
  • Wetting flows (anytime)
  • Wetting flows (anytime)
  • Substantial drawdown (August–April)
  • Wetting flows (February– May)
  • Wetting flows (August–November)
  • Wetting flows (anytime)
  • Substantial drawdown (August–March)
  • Wetting flows (February–May)
  • Flushing/wetting flows (August–November)
  • Partial drawdown (December–March)
  • Wetting flows (February–May)
  • Wetting flows (anytime)

Possible volume of environmental water required to achieve objectives

0–5,800 ML

0–5,800 ML

0–5,800 ML

0 ML

Heart Morass

Potential watering actions

  • Complete drawdown (July–June)
  • Wetting flows (anytime)
  • Wetting flows (anytime)
  • Partial drawdown (August–April)
  • Wetting flows (February–May)
  • Wetting flows (August–November)
  • Partial drawdown (August–March)
  • Wetting flows (February–May)
  • Wetting flows (anytime)
  • Flushing/wetting flows (August–November)
  • Partial drawdown (December–March)
  • Wetting flows (February–May)
  • Wetting flows (anytime)

Possible volume of environmental water required to achieve objectives

0–7,100 ML

0–7,100 ML

0–7,100 ML

0 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.