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The central Murray wetland system consists of 11 wetlands on the lower Loddon River and River Murray floodplains.

The central Murray wetlands are almost wholly contained within the Torrumbarry Irrigation Area and are all wetlands of regional or international significance. The area has experienced dramatic changes since European settlement with the construction of levees, roads and channels. Most of the wetlands are now cut off from natural flooding and rely on environmental water to maintain their ecological character and health.

Nine of the wetlands can receive environmental water using permanent infrastructure: Lake Cullen, Hird Swamp, Johnson Swamp, Round Lake, McDonalds Swamp, Lake Elizabeth, Lake Murphy, Richardson's Lagoon and the Wirra-Lo wetland complex. To date, neither Guttrum or Benwell forests, which both border the River Murray, have permanent infrastructure to deliver environmental water. Some of the semipermanent wetlands in these forests can receive environmental water via temporary pumping from the River Murray.

System map

Environmental watering objectives in the Central Murray wetlands

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Maintain and rehabilitate river red gum, black box, lignum woodland and wetland plant communities
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Provide appropriate wetting and drying conditions to support seed germination, seedling survival and recruitment including of semi-aquatic plant species in damp areas of wetlands
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Manage the extent and density of invasive plant species including Tall Marsh vegetation. Support a mosaic of wetland plant communities to provide feeding and breeding habitat for a diversity of native animals
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Maintain habitat for the critically endangered Murray hardyhead
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Provide habitat for waterbird resting, feeding and breeding including threatened species (such as Australasian bittern, little bittern and brolga)
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Provide habitat for the endangered growling grass frog

Environmental values

The wetlands in the central Murray system support vulnerable or endangered species including the Australasian bittern, Murray hardyhead, Australian painted snipe and growling grass frog. The wetlands provide habitat for many threatened bird species (including the great egret and white-bellied sea eagle) listed under several Acts and international agreements. Internationally recognised, Ramsar-listed wetlands in the system include Lake Cullen, Hird Swamp and Johnson Swamp, while others are of bioregional significance.

Social, cultural and economic values

The Barapa Barapa, Yorta Yorta and Wamba Wamba Nations are the Traditional Owner groups of the central Murray wetlands. The area is considered one of the most archaeologically important areas of Victoria with numerous middens, mounds, artefacts, scar trees and surface scatters documented. These Nations continue to have a connection to the central Murray wetlands. 

The wetlands are used for various recreational activities including birdwatching and bushwalking, and some wetlands are also used for duck hunting. Tourism is an important contributor to the local economy. Groundwater recharge and carbon storage are other indirect benefits of the wetlands.

Conditions mid-2017

High rainfall during winter/spring caused widespread flooding in the area, including of the Loddon and Avoca River floodplains. The wet conditions in 2016 followed more than three years of below-average rainfall, which shifted management of the wetlands from a planned dry scenario early in the season to a wet scenario by early-tomid- spring. Environmental watering focused on sites that remained isolated from natural flooding — via channels, roads and levees — as well as the delivery of large wetland watering actions that could not be achieved without assistance from natural floods.

Environmental watering in 2016–17 included top-up flows to Round Lake and Lake Elizabeth to maintain and establish suitable conditions for Murray hardyhead, and to Richardson's Lagoon, McDonalds Swamp, Hird Swamp and Wirra–Lo wetland complex to support the diverse waterbirds, plants and other animals typical of temporary freshwater marshes.

Before 2016–17, Lake Cullen had remained dry since 2012. Under the optimum watering regime, the wetland was due for a fill in the 2016–17 season, but due to the potential for groundwater interaction watering was only proposed if the neighbouring Avoca Marshes and Lake Bael Bael filled first. Heavy rainfall in September and October 2016 saw flooding in the Avoca River and subsequently of Lake Bael Bael. First and Second Marsh filled naturally. Environmental water was used to partially fill Lake Cullen in spring 2016 and supply top-ups in summer and autumn, which provided waterbird feeding and breeding habitats throughout the watering year. The nationally endangered Australasian bittern, Australian little bittern, brolga, magpie geese, whiskered tern and Australian shoveller were also recorded using the tall marsh habitat at the wetland.

Two of the wetlands in the central Murray system — Johnson Swamp and Lake Murphy — did not receive any floodwater or environmental water during 2016–17. Lake Murphy dried in January 2016 and remained dry for the entire year, helping to promote the germination and establishment of vegetation (such as river red gums) in and around the wetland. Johnson Swamp was allowed to draw down and dry following managed deliveries in the previous year, providing habitat for a large number of frogs and waterbirds including breeding brolga and black swan recorded in November 2016. The drawdown phase promoted highly productive mudflat habitat, important for the establishment of amphibious plant species.

Round Lake remained permanently inundated during the season to support the resident Murray hardyhead population. While fish surveys in autumn 2016 detected the presence of the fish, environmental DNA sampling in winter 2016, which detects species by analysing the DNA released by organisms into the environment, did not detect any Murray hardyhead DNA. A negative result from the new technology reflects the difficulties sampling for this species, especially in cooler months when populations are naturally lower. A recommendation was made to repeat surveys in spring and summer when populations are typically higher, if funding allows. Waterbird surveys in spring and summer recorded at least 21 species, with large numbers of Eurasian coot and black swans.

Lake Elizabeth continued to show a high coverage of aquatic plant species favoured by Murray hardyhead since the first environmental watering in 2014. The plants provide ideal habitat for the fish that were translocated into the wetland during spring and autumn in 2015.Waterbird surveys at Lake Elizabeth show that the variety of species and number of waterbirds are at their highest since monitoring began in 2012. The survey in January 2017 recorded up to 7,500 Eurasian coot, large populations of grey teal and threatened species such as freckled duck, blue-billed duck, hard head and Australasian shoveler present at the wetland.

Richardson's Lagoon spring and summer surveys recorded a lower number of waterbirds in comparison to other wet years, although there was still a variety of species and evidence of black swan, pacific black duck, grey teal and dusky moorhen breeding.

The Wirra–Lo wetland complex supported a high diversity of waterbird and woodland bird species in its five wetlands and the creeks adjoining them including the plumed whistling duck, hardhead, Australian wood duck, royal spoonbill, straw-necked ibis and the vulnerable grey-crowned babbler. The previously planted wetland plant species had flourished and spread naturally through the wetland: they include water ribbon, water milfoil, wavy marshwort, swamp buttercup and floating swamp wallaby-grass.

McDonalds Swamp waterbird surveys recorded a large variety and number of waterbirds. This included significant species listed in the Victorian Flora and Fauna Guarantee Act 1988: the intermediate egret, Australasian bittern, magpie geese, blue-billed duck, royal spoonbill, greycrowned babbler, migratory glossy ibis and Latham's snipe. Successful breeding of black swan, pink-eared duck, Australian wood duck, Eurasian coot, black-winged Stilt, red-kneed dotterel, Australian shelduck, pacific black duck, grey teal and purple swamphen was also recorded.

The environmental water delivered to Hird Swamp in late autumn 2017 has provided habitat for a large number of feeding waterbirds. It is expected that the upcoming bird surveys at the wetland will establish that large numbers and species of waterbirds will use the wetland in 2017–18.

Guttrum and Benwell forests received natural inflows during winter and spring 2016 from the high flows in the River Murray. The natural flooding allowed wetland and aquatic plants to germinate and flower in some parts of the forest, although in most parts of the forest the understorey is still in poor condition. Reed Bed Swamp (in Guttrum Forest) had little-to-no wetland vegetation recorded despite the recent flooding. Much of the forest is still recovering from the Millennium Drought and requires a more-natural watering regime and the reduction of grazing pressure to support recovery.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for central Murray wetlands

Potential environmental watering

Environmental objectives

Wetland watering

Round Lake (top-ups as required to maintain water-quality targets)

  • Maintain habitat for Murray hardyhead
  • Maintain suitable waterbird habitat

Lake Elizabeth (top-ups as required to maintain water-quality targets)

  • Maintain habitat for translocated Murray hardyhead
  • Support submerged salt-tolerant aquatic plant assemblage and a high diversity of waterbirds

Wirra–Lo wetland complex (top-ups as required to maintain depth)

  • Rehabilitate river red gum and a variety of aquatic vegetation communities, providing suitable habitat for the growling grass frog and a high diversity of waterbirds including brolga

Hird Swamp West and East (fill in winter/spring and provide top-ups if required to support bird breeding)

  • Optimise the benefits of autumn/winter partial fill and trigger an earlym waterbird breeding event
  • Maintain a variety of vegetation communities (including open-water habitat) to support waterbird feeding and breeding habitats

Richardson's Lagoon (fill in winter/spring and provide top-ups if required to support bird breeding)

  • Promote germination, growth and recruitment of a variety of floodplain plant species
  • Maintain a variety of water-dependent species including fish, waterbirds, frogs and turtles

Guttrum and Benwell forests (fill Reed Bed Swamp in winter/spring and provide top-ups if required to support bird breeding)1

  • Rehabilitate a variety of aquatic vegetation, semi-aquatic vegetation and river red gum communities in semipermanent wetlands that received natural flooding in 2016–17
  • Provide refuge habitat for waterbirds and water-dependant animals
  • Support colonial waterbird breeding, if it occurs

McDonalds Swamp (partial fill in autumn/winter)

  • Promote a variety of vegetation communities by supporting juvenile river red gums and reduce the spread of tall marsh
  • Facilitate early plant germination and provide suitable conditions for winter frog breeding

Lake Murphy (partial fill in autumn/winter)

  • Promote the growth of a variety of vegetation communities including recently planted juvenile river red gums to support waterbird and frog feeding and breeding habitats

Wetland drying

Johnson Swamp (drying) and Lake Cullen (drawdown)

  • Not to be actively watered in 2017–18
  • The drying phase of Johnson Swamp will help maintain a variety of habitats (such as herbland meadows) to support a range of waterbirds and animals; drying may also assist with the management of large reed encroachment
  • Lake Cullen will be allowed to draw down to maintain the salt tolerant wetland plant communities and provide a variety of habitat types to support a diversity of waterbirds

1 Guttrum and Benwell forests may receive environmental water in 2017–18 pending further investigation by North Central CMA. Infrastructure projects for Guttrum and Benwell forests are being assessed as part of the Sustainable Diversion Limit Offset mechanism of the Murray– Darling Basin Plan. Until works are approved and completed, environmental watering will only consider semipermanent wetlands that can receive water pumped from the River Murray.

Risk management

In preparing its seasonal watering proposal, North Central 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 Mallee region are involved in decisions about Murray river system, including its wetlands, anabranches, tributaries and floodplains, including Hattah Lakes.

Who is engaged and how

Recreational users

The Mallee Catchment Management Authority meets with recreational users (such as fishers, bushwalkers, various 'Friends of...' groups) on an ad-hoc basis, where recreational users have an opportunity to communicate their priorities and perspectives. A gap in engagement is anglers as there is not an organised representative group.

Parks Victoria is the land manager for many of the sites that receive environmental water. Parks Victoria notifies recreational users about planned environmental water deliveries and communicates the potential impacts of environmental watering (through their website and on-site public signage).

Environment groups

The Catchment Management Authority engages environment groups (such as the Field Naturalists, Landcare and Birdlife Australia) through direct meetings 2-3 times a year. These groups provide advice, communicate their priorities and are keen to understand environmental watering objectives and outcomes. Some groups also provide information on the outcomes of environmental watering (e.g. through bird surveys.)

Landholders/farmers

The Catchment Management Authority engages the Victorian Farmers Federation, and industry groups such as table grape growers, dried fruit growers, citrus growers and landholders with river frontage or private wetlands.

These groups are engaged on environmental water planning (long term and annual scoping) and environmental water delivery. These groups are also engaged on related projects such as the Sustainable Diversion Limit adjustment proposals.

Traditional Owners

There are representatives from multiple Traditional Owner Nations from the Mallee region on the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Office and the Murray-Darling Basin Association engage the Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Through the Catchment Management Authority Indigenous facilitator, individual Aboriginal stakeholders and groups are directly engaged throughout the year via the Catchment Management Authority Aboriginal Reference Group.

Councils

The Catchment Management Authority engages with the Mildura and Swan Hill Rural City Councils quarterly. Councils provide advice on potential community impacts of environmental watering and communicate environmental watering information back to the broader community.

General public

The Catchment Management Authority engages and communicates with the general public about environmental watering via SMS, their website, publications and media releases.