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he 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 lower Latrobe wetlands. Construction of levees and drains and the filling in of natural depressions have also altered water movement into and through the wetlands. The drainage and flooding regime in all three wetlands is now managed to some extent by using regulators connected to the Latrobe River.

Storage manager
Environmental water holder

Environmental watering objectives in the lower Latrobe wetlands

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Provide habitat for waterbirds
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Reduce the abundance of carp, particularly at Sale Common and Dowd Morass
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Increase dispersal and germination of wetland plants

Environmental values

The lower Latrobe wetlands (Dowd Morass, Heart Morass and Sale Common) are an important component of the internationally recognised Gippsland Lakes Ramsar site and provide habitats for a variety of waterbirds. Colonial waterbirds (such as royal spoonbill and straw-necked and Australian white ibis) breed in spring among the swamp paperbark trees at these wetlands. Migratory shorebirds (such as sandpipers) feed on the mudflats that are exposed as the wetlands draw down and dry over summer. Waterfowl and fish-eating birds (such as egrets) use available open-water habitat at the wetlands year-round.

Saltwater intrusion from the Gippsland Lakes is a constant threat to environmental values in Dowd Morass and Heart Morass. Rising sea levels from climate change will continue to exacerbate that threat. Although Heart Morass's vegetation has been degraded by many years of grazing, much wetland on private property is now recovering with the aid of restoration programs. The establishment and growth of aquatic vegetation is affected by carp in all wetlands. An invasive aquatic weed, Brazilian milfoil, has colonised much of the fringe of Sale Common, whereas its spread to Heart Morass and Dowd Morass is probably limited by salinity in those wetlands.

Social, cultural and economic values

Sale Common is a state game refuge located close to the city of Sale that provides an excellent opportunity to observe native plants and animals. Dowd Morass is a state game reserve commonly used by hunters. 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 provides opportunities for birdwatching and hunting when the wetlands are in a wet phase.

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

Conditions mid-2017

Although inflows to the wetlands were infrequent and small-scale in 2016–17, inflows from the Latrobe River to Sale Common, Dowd Morass and Heart Morass did occur in winter. The 2016–17 summer and autumn was quite mild, and the wetlands' levels have not receded as much as they did the previous year.

In Sale Common, there was an excellent environmental response in winter. Filling began slowly in June, providing clear water that prompted good growth of aquatic vegetation. Vegetation growth was helped by the low abundance of carp, which were screened from the wetland. A larger overbank flow in July inundated the wetland with more turbid water and lots of carp, but it also triggered the largest breeding event of black swans locals have seen in a decade.

A combination of low water levels in Dowd Morass, a strong easterly wind and a high tide caused saltwater intrusion from Lake Wellington to Dowd Morass in May 2016. Salinity increased in Dowd Morass to almost half that of seawater (19,000 EC), threatening the condition of swamp paperbark that ibis and spoonbill use for nesting. Regulators to Dowd Morass from the Latrobe River are old and were not designed to manage environmental water. On their own, the regulators cannot provide the necessary volume of freshwater from the Latrobe River to dilute salt build-up in Dowd Morass. Large natural inflows in July eventually reduced salinity to about 4,000 EC and the main regulator to Dowd Morass has remained open all year to allow as much mixing as possible. Despite this, salinity levels remained higher than the desired threshold. New regulators for managing environmental flows in Dowd Morass and Heart Morass have been designed and will be constructed when funding is available.

Although salt water intruded into Heart Morass in 2016, the impacts were not severe because levees protected it from Lake Wellington and the wetland was partially filled with environmental water from the Latrobe River in autumn 2016. The environmental water provided in March–May 2016 was the first delivery to Heart Morass under the Lower Latrobe Wetlands Environmental Entitlement 2010. The delivery was made with the agreement of private property owners in the wetland, and it provided great benefit for swans that fed on the wetland plants that germinated as a result of the delivery.

Scope of environmental watering

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

Potential environmental watering

Environmental objectives

Sale Common

Fill or partial fill (July–November)

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

Fill or partial fill (any time)

  •  Control invasive plants and algae
Partial or complete drawdown (year-round, primarily August–March)
  • Oxygenate surface soils, break down accumulated organic matter and cycle nutrients
  • Increase the growth and recruitment of wetland plants across the wetland bed
  • Reduce the abundance of European carp
Fill or partial fill (February–May)
  • Provide feeding and sheltering habitat for wetland animals, particularly waterbirds and frogs
  • Restrict the spread of giant rush

Dowd Morass and Heart Morass

Fill or partial fill (Dowd Morass: July–November) (Heart Morass: July–December)

  • Trigger colonial waterbird breeding
  • Reduce salinity
  • Increase the growth and recruitment 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
Partial or complete drawdown (year-round, 
primarily August–March)
  • Oxygenate surface soils, break down accumulated organic matter and cycle nutrients
  • Increase the growth and recruitment of wetland plants, particularly swamp shrub, tall marsh, aquatic herbland and brackish herbland
  • soils, Reduce the abundance of European carp
Fill or partial fill (February–May)
  •  Provide feeding habitat for wetland animals, particularly waterbirds
Fill or partial fill (any time)
  •  Control salinity and reduce the risk of acid sulphate soils

Risk management

In preparing its seasonal watering proposal, West Gippsland 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.

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.