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Regulation and diversion of River Murray flows have substantially reduced the frequency and duration of the high river flows that would naturally water the lower Murray wetlands. This change to the water regime has reduced the variety and condition of environmental values associated with billabongs and other floodplain habitats.

Water for the environment can be delivered to some wetlands in the region by direct pumping from the River Murray and/or use of irrigation supply infrastructure. Most wetlands that receive environmental flows can be managed independently of each other.

Some wetlands in the lower Murray area can receive water through weir-pool manipulation, for improved environmental outcomes. However, because they do not receive held water for the environment, they are not specified in this plan. Details of the environmental objectives associated with those wetlands can be found in the Mallee CMA’s Seasonal Watering Proposal for the Lower Murray Wetlands 2019–20.

System map

Environmental watering objectives in the Lower Murray wetlands

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Maintain and/or grow populations of native fish in permanent wetlands
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Maintain and/or grow populations of native frogs including the endangered growling grass frog
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Provide habitat for large terrestrial animals (such as lace monitors and bats)
Maintain and/or grow populations of native freshwater turtles including the endangered broad-shelled turtle
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Increase the diversity, extent and abundance of wetland plants

Improve the condition of river red gums, black box and lignum
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Provide feeding and breeding habitat for a range of waterbird species including threatened and migratory species and colonial nesting species (such as egrets)

Environmental values

The lower Murray wetlands are comprised of multiple wetlands, creeks and billabongs. Depending on their location in the landscape, interactions with groundwater and their management history, the wetlands may be permanent or temporary, freshwater or saline. Differences
in water regime and water quality between the wetlands provide a range of habitats for plants and animals. For example, permanent, saline wetlands (such as Brickworks Billabong) provide vital habitat for the endangered Murray hardyhead fish. Ephemeral wetlands support different ecological processes in their wet and dry phases. During the wet phase, they provide short-term boom periods when river red gum trees and wetland plants grow, spread and provide habitat for aquatic animals (such as waterbugs, birds, frogs and in some cases fish). During the dry phase, sediments are exposed to the air (which is important for carbon and nutrient cycles), and terrestrial plants grow and complete life cycles.

Recent conditions

The lower Murray wetlands area experienced lower-than- average rainfall and higher-than-average temperatures in 2018–19. Although local rainfall is a contributing factor, flows in the River Murray primarily determine the inundation frequency and duration of the lower Murray wetlands. A small pulse in the River Murray in October 2018 inundated some of the low-lying wetlands in the area, but the flow was not sufficient to inundate any of the wetlands specified in the Seasonal Watering Plan 2018–19.

Environmental watering was managed under a dry scenario throughout 2018–19, prioritising watering actions that aimed to protect and maintain environmental values, avoid critical losses and maintain key refuges and key ecosystem functions at high-priority wetlands.

Water for the environment was delivered to nine wetlands in the lower Murray system. Most of this water was used to partially or completely fill wetlands in spring. Prolonged high temperatures over spring/summer resulted in increased evaporation, and water levels declining faster than normal. Top-ups were provided as needed to Lake Hawthorn, Koorlong Lake and Brickworks Billabong, to maintain water quality and ruppia aquatic habitat for Murray hardyhead.

Water for the environment was delivered to Lake Hawthorn in spring 2018 to provide optimal conditions for about 600 captive-bred Murray hardyhead that were released into the lake. Competing water demands prevented subsequent top-ups to the lake in January 2019: water for the environment uses the existing irrigation network for delivery and is subject to interruptible supply to meet irrigation demands. Monitoring in 2019 will determine if spawning and recruitment has been successful.

Following spring fills, the regulators to both Butlers Creek and Ducksfoot Lagoon were closed, allowing the wetlands to draw down over summer and autumn. Drying of the wetlands will help control local populations of carp. A large number of waterbirds including spoonbills and egrets were observed at both wetlands, after the wetlands filled and as they drew down.

In autumn, water for the environment was delivered to Lake Hawthorn, Burra Creek North, Burra Creek South and Vinifera floodplain. Except for Lake Hawthorn, these wetlands were allowed to completely dry over spring/ summer. Drying killed carp that had moved into the wetlands and allowed clays in the bed of the wetlands to crack, which provided habitat for insects, reptiles and small mammals and allowed carbon/nutrients to accumulate in the soil. The input of carbon and nutrients during the dry phase will lead to increased productivity when the wetlands are next watered.

Scope of environmental watering

Potential environmental watering actions and objectives for the lower Murray wetlands

Potential environmental watering action

Functional watering objective

Environmental objectives

Wetland watering

Brickworks Billabong (fill in spring, with top-ups as required to maintain water quality and water level targets)

  • Inundate existing river red gum, black box and lignum to maintain/ improve their condition
  • Promote the growth of seasonal emergent and semi-emergent macrophytes
  • Provide seasonal connectivity along Burra Creek, wetlands and the floodplain to increase the movement of turtles to support their recruitment and long-term population growth
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Bridge Creek (fill in winter/ spring)

  • Inundate existing fringing river red gum, black box and lignum to maintain/improve their condition
  • Promote the growth of seasonal emergent and semi-emergent macrophytes
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Bullock Swamp North (fill in winter/spring)

  • Inundate the existing mature river red gum trees along the wetland perimeter to maintain their health
  • Inundate the floodway pond herbland EVC1 within the creek to provide seasonal aquatic habitat that supports a diverse population of native fish and frogs
  • Inundate the intermittent swampy woodland EVC1 to provide nesting and feeding habitat for waterfowl in winter and spring
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Burra Creek North (fill in winter/spring)

  • Inundate the existing river red gum communities to improve their health
  • Inundate the floodplain to increase the recruitment of floodplain plant communities including river red gum, lignum and black box
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Burra Creek South (fill in winter/spring)

  • Fill wetland to 38.0 m AHD in spring to support the growth of ruppia, to provide nursery habitat for Murray hardyhead and provide high levels of aquatic productivity
  • Allow water levels to drop over summer to 36.7 m AHD to increase salinity levels, providing a competitive advantage to Murray hardyhead
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Burra Creek South Proper (fill in winter/spring)

  • Inundate trees (including river red gum) bordering creeks and lakes to improve their condition
  • Fill Lake Carpul to capacity to support water-dependent vegetation and increase understorey productivity
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Carina Bend (fill in winter/ spring)

  • Fill wetland to 33.3 m AHD to encourage the germination and growth of ruppia, to provide nursery habitat for Murray hardyhead and visitation by shorebirds
  • Allow natural recession of a maximum 0.3 m (to 33.0 m AHD) to expose mudflats for foraging shorebirds before providing a top-up volume to return the water level to 33.3 m AHD
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J1 Creek (fill in winter/ spring)

  • Inundate trees (including river red gum) bordering creeks and lakes to improve their condition
  • Fill Lake Powell to capacity to support water-dependent vegetation and increase understorey productivity
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Koorlong Lake (top-ups as required to maintain water quality and water level targets)

  • Fill wetland to 38.0 m AHD in spring to support the growth of ruppia, to provide nursery habitat for Murray hardyhead and provide high levels of aquatic productivity
  • Allow water levels to drop over summer to 36.7 m AHD to increase salinity levels, providing a competitive advantage to Murray hardyhead
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Lake Carpul (fill in winter/ spring)

  • Inundate trees (including river red gum) bordering creeks and lakes to improve their condition
  • Fill Lake Carpul to capacity to support water-dependent vegetation and increase understorey productivity
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Lake Hawthorn (fill in spring, with top-ups as required to maintain water quality and water level targets)

  • Fill wetland to 33.3 m AHD to encourage the germination and growth of ruppia, to provide nursery habitat for Murray hardyhead and visitation by shorebirds
  • Allow natural recession of a maximum 0.3 m (to 33.0 m AHD) to expose mudflats for foraging shorebirds before providing a top-up volume to return the water level to 33.3 m AHD
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Lake Powell (fill in winter/ spring)

  • Inundate trees (including river red gum) bordering creeks and lakes to improve their condition
  • Fill Lake Powell to capacity to support water-dependent vegetation and increase understorey productivity
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Liparoo East Billabong (fill in winter)

  • Fill the billabong to encourage lignum growth and provide feeding habitat for large waders as well as temporary breeding habitat for waterbirds
  • Fill the billabong to support the growth of native vegetation and increase the understorey diversity and recruitment of river red gum saplings
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Liparoo West Billabong (fill in winter)

  • Fill the billabong to encourage lignum growth and provide feeding habitat for large waders as well as temporary breeding habitat for waterbirds
  • Fill the billabong to support the growth of native vegetation and maintain a community of drought-tolerant emergent aquatic macrophytes at the wetland edge
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Neds Corner Central (fill in spring/summer)

  • Fill the wetland to inundate the lignum swamp zone to stimulate the recruitment of native vegetation and improve species diversity
  • Fill the wetland to encourage lignum growth and increase the quantity and quality of nesting habitat for waterbirds
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Neds Corner East (fill in spring/summer)

  • Fill the wetland to inundate the floodway pond herbland zone, to stimulate the recruitment of native vegetation and improve species diversity
  • Improve vegetation recruitment and diversity to meet EVC1 benchmarks * Maintain the health and structure of the shrubby riverine woodland EVC1
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Neds Corner Woolshed (fill in winter/spring)

  • Inundate the creek bed to enhance floodplain productivity and provide increased foraging areas to support the growling grass frog population
  • Fill the creek to increase the recruitment of river red gums and understory shrubs to improve breeding and nesting opportunities for native waterbirds
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Nyah Floodplain (fill in spring/summer)

  • Water seasonal anabranches to restore the vegetation structure of wetland plant communities
  • Fill seasonal wetlands to re-establish resident populations of native frogs and support terrestrial animals
  • Inundate the red gum swamp forest and woodland to increase the recruitment of river red gum saplings and provide reliable breeding habitat for waterbirds including colonial nesting species
  • Deliver water onto the floodplain to improve the vegetation condition and support resident populations of vertebrate animals including carpet python, sugar glider and grey-crowned babbler
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Vinifera Floodplain (fill in spring/summer)

  • Water seasonal anabranches to restore the vegetation structure of wetland plant communities
  • Fill seasonal wetlands to re-establish resident populations of native frogs and support terrestrial animals
  • Inundate the red gum swamp forest and woodland to increase the recruitment of river red gum saplings and provide reliable breeding habitat for waterbirds including colonial nesting species
  • Deliver water onto the floodplain to improve the vegetation condition and support the resident populations of vertebrate animals including carpet python, sugar glider and grey-crowned babbler
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Yungera Wetland (fill in winter/spring)

  • Inundate the existing river red gum communities to improve their health
  • Inundate the floodplain to increase the recruitment of floodplain plant communities including river red gum, lignum and black box
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Wetland drying

Margooya Lagoon

  • Allow the lagoon to naturally recede and dry, to remove carp from the system and allow soils to consolidate and crack, to promote nutrient cycling. This promotes high levels of aquatic productivity upon rewetting, which support native frogs, fish recruitment and a range of habitat for waterbird feeding and breeding
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Engagement

Table 2 shows the partners and stakeholder organisations with which Mallee CMA engaged when preparing the lower Murray wetlands seasonal watering proposal.

Seasonal watering proposals are informed by longer-term regional catchment strategies, regional waterway strategies, environmental flow studies, water management plans and other studies. These incorporate a range of environmental, cultural, social and economic perspectives and longerterm integrated catchment and waterway management objectives. For further details, refer to the Mallee Regional Catchment Strategy and the Mallee Waterway Strategy

Table 2 Partners and stakeholders engaged in developing the lower Murray wetlands seasonal watering proposal

Partner and stakeholder engagement
  • Mid-Murray Field Naturalists Incorporated Association
  • Mallee Tours
  • Mildura Information Centre
  • Murray Offroad Adventures
  • Sunraysia Apiarist Association
  • Visit Mildura
  • Wildside Outdoors
  • Mildura Rural City Council
  • Murray-Darling Basin Authority
  • Parks Victoria
  • Victorian Environmental Water Holder
  • Department of Environment, Land, Water and Planning
  • Goulburn-Murray Water
  • Mildura Birdlife Club
  • Sunraysia Bushwalkers
  • Wadi Wadi Traditional Owners and the broader Aboriginal community