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The central Murray wetland system consists of ten wetlands on the River Murray floodplain. Nine of these can receive environmental water: Lake Cullen, Hird Swamp, Johnson Swamp, Round Lake, McDonalds Swamp, Lake Elizabeth, Lake Murphy, Richardsons Lagoon and the Wirra–Lo wetland complex. These are all wetlands of regional significance.

The central Murray wetlands are almost wholly contained within the Torrumbarry Irrigation Area. This 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 the provision of environmental water to maintain their ecological character and health.

Guttrum and Benwell forests are a regionally significant wetland system and border the River Murray. Neither forest has permanent infrastructure to deliver environmental water although some semipermanent wetlands can be watered via temporary pumping from the River Murray.

System map

Murray System

Environmental watering objectives in the Central Murray wetlands

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Provide habitat for waterbird resting, feeding and breeding
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Maintain habitat for the critically endangered Murray hardyhead
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Provide habitat for the endangered growling grass frog
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Maintain river red gum, black box, lignum woodland and wetland plant communities
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Provide appropriate wetting and drying conditions that support seed germination, seedling survival and recruitment including of semi-aquatic plant species in damp areas of wetlands

Environmental values

The wetlands within the central Murray system are highly significant, supporting 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 a range of legislation and international agreements. There are internationally recognised, Ramsar-listed wetlands within the system including Lake Cullen, Hird Swamp and Johnson Swamp, while the others are of bioregional significance.

Social 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.

The wetlands are used extensively for various recreational activities including bird watching, bushwalking and duck hunting in some wetlands. Tourism to the region supports the local economy and other indirect economic benefits are derived from groundwater recharge and carbon storage that the wetlands support.

Conditions mid-2016

Significantly low rainfall, high temperatures and barriers - channels, roads and levees - that prevent natural run-off meant that minimal natural inflows were received in the central Murray wetlands in 2015–16. Environmental water was the primary water source provided in 2015–16.

Environmental watering in 2015–16 included top-up flows to Round Lake and Lake Elizabeth to maintain and establish suitable conditions for Murray hardyhead; and to Johnson Swamp, Richardson's Lagoon and Wirra–Lo wetland complex to support a diversity of waterbirds, plants and other animals typical of temporary freshwater marshes.

Four of the wetlands in the central Murray system did not receive environmental water in 2015–16 including McDonalds Swamp, Hird Swamp, Lake Cullen and Lake Murphy. A partial fill of McDonalds Swamp planned for autumn 2016 did not go ahead due to the risk of introducing high levels of toxic blue-green algae from the irrigation system into the wetland. The delivery to McDonalds Swamp is now planned to occur in late winter to early spring 2016. A drying regime was implemented for Hird Swamp, Lake Cullen and Lake Murphy: this helps promote germination and establishment of vegetation in and around the wetland and also promotes productivity and provides an important food source for wading waterbirds.

The drying of Lake Murphy resulted in a very productive mudflat and shallow water habitats that supported a diversity of feeding and breeding waterbirds into mid-summer including at least 1,000 individuals of 25 different waterbird species.

Round Lake remained permanently inundated during the season to support the resident Murray hardyhead population. While fish surveys in spring 2015 did not catch any Murray hardyhead individuals, surveyors observed some of the fish congregating in the shallower areas of the wetland. A low catch rate reflects the difficulties sampling for this species and its natural boom-and-bust population cycles.

In Lake Elizabeth the coverage of aquatic plant species favoured by Murray hardyhead have become more widespread since the first environmental watering in 2014. The plants should provide ideal habitat for the Murray hardyhead that were translocated into the wetland in autumn 2016.

A large variety and number of waterbirds were recorded at Wirra–Lo wetland complex, Johnson Swamp and Richardsons Lagoon in 2015–16. This included significant species listed in the Victorian Flora and Fauna Guarantee Act 1988: the intermediate egret, Australasian bittern, little bittern, blue-billed duck, royal spoonbill, Baillon's crake, Latham's snipe, painted snipe and brolga. Successful breeding of Australasian bittern, Australian little bittern and brolga was recorded at Johnson Swamp. Other threatened species such as the sharp-tailed sandpiper, marsh sandpiper and whiskered tern were also recorded at some of these wetlands.

Wirra–Lo wetland complex was part of a former irrigation property that has been prioritised for rehabilitation with the strong support of the landholders. The landholders used irrigation water run-off and altered irrigation infrastructure to maintain the wetland's integrity for years. The wetland now has an environmental covenant to protect the land from farming and has been voluntarily disconnected from the irrigation network. Environmental water was first delivered to the Wirra–Lo wetland complex in 2014 and follow-up watering occurred in 2015–16. Each watering has triggered the rapid growth of aquatic and amphibious plant species (such as wavy marshwort, robust milfoil and spiny mud-grass). Environmental water in combination with land rehabilitation works and a native vegetation planting program is supporting a diverse range of wetland animal species including frogs and waterbirds. 

Guttrum and Benwell forests have not received natural inflows since the heavy rains and consequent high flows in the River Murray in 2010–11. Although the natural inundation assisted the forest to partly recover from the millennium drought, recent observations suggest that the forests are still in relatively poor condition and require a more natural watering regime and reduced grazing pressure to support their 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-up flows as required to maintain water quality targets)

  • Maintain habitat for Murray hardyhead
  • Maintain suitable waterbird habitat

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

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

Wirra–Lo wetland complex (fill in winter/spring and provide top-ups if required)

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

Guttrum and Benwell forests (semipermanent wetlands only; fill in winter/spring and provide top-ups if required) 1

  • Promote a variety of aquatic vegetation, semi-aquatic vegetation and river red gum communities in semipermanent wetlands
  • Provide feeding and breeding habitat for waterbirds

McDonalds Swamp (fill in winter/spring and provide top-ups if required)

  • Maintain a diverse vegetation community by supporting juvenile river red gums and reducing coverage of common reed and cumbungi communities through environmental water management

Richardsons Lagoon (top up in winter/spring and provide top-ups if required)

  • Promote a variety of aquatic plant species that support a variety of water-dependent species including fish, waterbirds, frogs and turtles

Hird Swamp West and East (partial fill in autumn/winter)

  • Maintain a variety of vegetation communities (including open-water habitat) to support waterbird feeding and breeding habitats

Lake Cullen (top up in spring if natural flooding occurs)

  • Maintain a viable stock of submerged salt-tolerant aquatic plants to support waterbird feeding and breeding habitats

Wetland drying

Johnson Swamp and Lake Murphy (drawdown and drying)

  • These wetlands will not be actively watered in 2016–17
  • The drying will assist in maintaining a diversity of habitats to support a wide range of wetland-dependent birds and animals and to promote the growth and establishment of vegetation in and surrounding the wetland

1 Guttrum and Benwell forest may receive environmental water in 2016–17 pending further investigation by North Central Catchment Management Authority. Infrastructure projects for Guttrum and Benwell forests are being assessed as part of the Sustainable Diversion Limit Offset component of the Murray–Darling Basin Plan. Until works are approved and completed, environmental watering will only consider semipermanent wetlands that can receive water that is pumped from the River Murray.

Scenario planning

Landscape-scale planning for these wetlands has been undertaken by the North Central Catchment Management Authority to optimise the wetland watering regimes over multiple years. An important consideration in this planning includes ensuring that there is a diversity of habitat types available across the region to support waterbirds and other water-dependent animals at any point in time.

In a given year, multiple wetlands may require environmental water at the same time. Inter-annual planning helps to manage this risk of increased pressure on environmental water resources, particularly if there is a return to drought conditions. It also helps support waterbird populations by ensuring that suitable habitat for breeding, feeding and nesting is available across northern Victoria.

The wetlands of highest priority for environmental water management in the central Murray wetlands in 2016–17 are Round Lake and Lake Elizabeth. Round Lake supports what is considered to be the only stable population of the critically endangered Murray hardyhead in the Kerang region. Murray hardyhead were also recently translocated to Lake Elizabeth and the lake will be prioritised to receive environmental water in 2016–17 to support the new population. It is important that these wetlands are maintained for future stocking and translocation programs to prevent the regional loss of the species.

In drier conditions, environmental water is planned to be delivered to fill and maintain water depth in some wetlands, to support the needs of wetland-dependent plants, fish and birds. Water availability may increase if catchment conditions become wetter, which would support delivery to more wetlands within the central Murray to help meet native plant, animal and waterbird objectives. Under very wet conditions natural floods may partially or completely fill some of the central Murray wetlands, but environmental water will be required to maintain water depth to support waterbird breeding and plant condition.

While environmental water is planned to be delivered to Lake Cullen in 2016–17, its significant size and potential groundwater issues means that delivery depends on a degree of natural inundation of the wetland which in 2016–17 would only occur under extremely wet conditions. If natural flooding does occur, environmental water may be used to top up and maintain water levels to reduce the potential detrimental impact from a short, shallow inundation and groundwater intrusion. Further assessment will be undertaken to inform the most appropriate management option considering the timing, extent and duration of any natural inundation. 

No environmental water is planned to be delivered to Johnson Swamp and Lake Murphy in 2016–17. These wetlands are undergoing a drying phase to promote habitat diversity for waterbirds and also to support young river red gums that established after recent environmental watering.

Table 2 Potential environmental watering for central Murray wetlands under a range of planning scenarios

Planning scenario

Drought

Dry

Average

Wet

Expected catchment conditions

  • Catchment run-off and unregulated flows into the wetlands is unlikely
  • Catchment run-off and unregulated flows into the wetlands is unlikely
  • Some catchment run-off and unregulated flows into the wetlands is likely, particularly in winter/spring
Catchment run-off and unregulated flows into the wetlands may significantly contribute to water levels in the wetlands, particularly in winter/spring

Potential environmental watering – tier 1 (high priorities)

  • Round Lake
  • Lake Elizabeth
  • Round Lake
  • Lake Elizabeth
  • Round Lake
  • Lake Elizabeth
  • Wirra–Lo wetland complex
  • Guttrum and Benwell forests
  • McDonalds Swamp
  • Richardsons Lagoon
  • Round Lake
  • Lake Elizabeth
  • Wirra–Lo wetland complex
  • Guttrum and Benwell forests
  • McDonalds Swamp
  • Richardsons Lagoon

Potential environmental watering – tier 2 (additional priorities)

  • Wirra–Lo wetland complex
  • Guttrum and Benwell forests
  • McDonalds Swamp
  • Richardsons Lagoon
  • Wirra–Lo wetland complex
  • Guttrum and Benwell forests
  • McDonalds Swamp
  • Richardsons Lagoon
Hird Swamp
  • Hird Swamp
  • Lake Cullen

Possible volume of environmental water required to meet objectives1

  • 3,850 ML (tier 1)
  • 5,175 ML (tier 2)
  • 3,100 ML (tier 1)
  • 4,300 ML (tier 2)
  • 7,400 ML (tier 1)
  • 1,500 ML (tier 2)
  • 7,400 ML (tier 1)
  • 19,000 ML (tier 2)

Priority carryover requirements

  • 3,900 ML
3,100 ML5,800 ML
  • 5,800 ML

2 Possible environmental water requirements for tier 2 are additional to tier 1 requirements.

Risk management

In preparing its seasonal watering proposal, North Central 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.

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.