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5.2.5 Lower Murray wetlands
System overview
The lower Murray wetlands are dispersed across the Murray River floodplain between Swan Hill and the South Australian border. The system includes a myriad of interconnected creeks, wetlands and floodplains that are ecologically important and reflect the natural character and attributes of the floodplain. While the number of wetlands across the lower Murray region are in their hundreds, about 54 of these have received water for the environment to date.
Regulation and diversion of Murray River 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 been exacerbated by climate change and 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 through direct pumping from the Murray River and/or use of irrigation supply infrastructure. Most wetlands that receive environmental flows can be managed independently of each other.
Some wetlands within the lower Murray region can receive water through weir pool manipulation and regulator operation, for improved environmental outcomes. However, because they do not receive held environmental water, they are not specified under 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 2020–21.
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 Koorlong Lake) 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.
Environmental watering objectives in the lower Murray wetlands
5.2 Victorian Murray system
     Maintain and/or increase populations of native fish in permanent wetlands
    Maintain and/or grow populations of native frogs including the endangered growling grass frog
   Increase the diversity, extent and abundance of wetland plants
Improve the condition of river red gums, black box and lignum
    Provide feeding and breeding habitat for a range of waterbird species including threatened and migratory species and colonial nesting species (such as egrets)
  Victorian Environmental Water Holder | Seasonal Watering Plan 2020–21 | 225

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