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Flows in the River Murray System

Flows in the River Murray System vary widely depending on a range of factors, including rainfall, inflows, evaporation, and demand for water for human use.

At any given time, water flowing through the river is destined for various uses, including irrigation, industry, communities, the environment, and meeting South Australia’s flow entitlement. The exact mix of these flow components is determined by demand and water availability, amongst other factors.

The graphic below is indicative of how water flow is managed throughout the seasons across a typical year.

Seasonal flow in the River Murray System, highlighting that water for environment flows are lower in summer-autumn, and higher in winter-spring.

  • River operations focus on managing dam storage levels and river system for the following water year
  • River flows are relatively stable
  • Medium demand for consumptive use (irrigation, industry, communities)
  • Water for the environment flows are low
  • Dam storage levels decline 
  • River operations focus on capturing inflows from tributaries and meeting early season demand*
  • River flows are highly variable
  • Lowest demand for consumptive water (irrigation, industry, communities)
  • Water for the environment flows increase
  • Dam storage levels increase
  • River operations aim to capture water inflows and manage dam storage levels for summer demand* 
  • Increasing demand for consumptive water (irrigation, industry, communities)
  • River flows are highly variable
  • Water for the environment flows are highest
  • Dam storage levels increase due to higher inflows
  • River operations focus on managing water supply to meet large system demand*
  • River flows are relatively stable
  • Highest demand for consumptive water (irrigation, industry, communities)
  • Water for the environment flows decrease
  • Dam storage levels decline

* including meeting South Australia's flow entitlement.

Water for the environment

Overall, water for the environment is a small percentage of the total water used in the Murray–Darling Basin. 

The volume of water for the environment used, under water entitlements has increased slightly over the past five years, as more water became available. The average use over this period was 20.4 per cent of the total water used in the Basin.

Importantly, water held for the environment uses the same entitlement framework as consumptive users. In any given year the amount of water available for delivery to key environmental sites is determined based on the same rules that apply to all other consumptive water uses.

Who holds and manages water for the environment


Flows in the River Murray System

Information in the figure above is for the month of October 2020 and may not include recent rainfall or delivery of water for the environment in the Murray system. Information in this figure is an average estimate over the past month and formal accounts from Basin state governments may vary. Water for the environment in the figure above represents water that is held by environmental water holders, through entitlements. Other water that flows through the river can also achieve environmental outcomes.

River flow information

With the return to regulated conditions in late September, the October flow to South Australia comprised of water for South Australian entitlement, as well as traded volumes and water for the environment.

Delivery of water for the environment continued during the month, with water delivered from the Lower Broken Creek, Campaspe River and Goulburn Rivers, as well as Hume Dam.

Intended environmental outcomes

Location Return flows used Intended environmental outcome(s)
River Murray Channel multi-site delivery N/A
  • provide flows that connect the River Murray from the source to the mouth
  • nourish wetlands, creeks and billabongs
  • following the higher rainfall, flows have started to increase to connect the river and floodplains and support Murray cod breeding
Barmah-Millewa Forest N/A
  • provide flows in forest waterways to maintain habitat for native fish and turtles
  • encourage movement of native fish between creeks and the river
  • flush organic matter from the forest waterways to cycle carbon and boost food production in the River Murray
Lower Broken Creek N/A
  • protect and increase native fish numbers
  • avoid excessive build-up of azolla fern
Edward-Wakool N/A
  • provide higher flows through the creek system to support native fish and fringing vegetation
Goulburn River N/A
  • protect and boost native fish numbers, maintain and improve abundant and diverse waterbugs
  • increase growth of water dependent plants in the river channel and stabilising riverbanks
Campaspe River N/A
  • provide habitat to help protect and boost native fish and maintain resident platypus numbers
Gunbower Creek  Yes
  • maintain breeding habitats and food resources for native fish such as Murray cod
Gunbower Forest - Reedy Lagoon and Black Swamp Yes
  • maintain wetland water depth and extent to support growth and survival of wetland plants.
  • provide feeding and refuge habitat for waterbirds, turtles, frogs and native fish
Pollack Swamp No
  • provide critical wetland refuge habitat for a range of native plants and animals
Thule Creek No
  • provide habitats to help protect and increase populations of native fish, maintain river red gum health
  • provide habitat for colonial nesting waterbird breeding
Buccaneit-Cunninyeuk creek system No
  • provide habitat to increase native fish numbers
  • maintain river red gum health
Tuppal Creek No
  • provide habitat to increase native fish numbers
  • maintain river red gum health
Cockrans-Jimaringle creek system No
  • provide habitat to increase native fish and southern bell frog numbers.
  • maintain river red gum health
Murrain-Yarrein creek system No
  • provide habitat to increase native fish and southern bell frog numbers
  • maintain river red gum health
Pyramid Creek No
  • maintain connectivity between pools
  • provide habitats for native fish and waterbugs
Lower Darling River No
  • small increase to baseflows to improve the condition of the Lower Darling (Baaka)
  • assist native fish recovery by supporting Murray cod nesting this Spring (and potentially golden perch and silver perch breeding)
Lindsay, Mulcra, Wallpolla Yes
  • provide healthy wetland refuge habitat for a range of native plants and animals supporting foraging and breeding of native waterbirds, fish, frogs and turtles
  • provide nursery habitat for naturally occurring fish populations, juvenile golden perch and silver perch stocked by Victorian Fisheries Authority
Chowilla floodplain Yes
  • provide healthy wetland refuge habitat for a range of native plants and animals
Pike and Katarapko floodplains  Yes
  • operate new environmental regulators to inundate floodplain areas to support the health and resilience of native vegetation, wetland and anabranch habitats
Lower Murray wetlands No
  • provide healthy wetlands refuge habitat for a range of native plants and animals
Lower Lakes, Coorong and Murray Mouth Yes
  • spring barrage releases for fish migration
  • to improve water quality and diversity of habitat in the Coorong
  • manage lake levels

Sharing River Murray water

For more than 100 years, the states have been sharing the waters of the Murray. The Murray–Darling Basin Agreement sets out the rules negotiated and agreed by New South Wales, South Australia, Victoria and the Australian Government.

The Murray–Darling Basin Authority (MDBA) facilitates the sharing of River Murray water based on the agreed rules. The MDBA determines releases in the River Murray System to meet expected demands from the states. A range of scenarios are considered and these are used to guide operations for the year. As the year unfolds the scenarios and options are updated and operations amended accordingly.

Identifying how much water is available to the states takes into consideration stored water and seasonal weather conditions. Of the available water the MDBA determines conveyance water, critical human water needs and reserve for the next season before it shares water to the states. Each state has developed its own set of entitlement licences and rules around how to allocate their share of water. This means allocations, water orders and delivery of water all work in a different way from state to state.

Updated: 13 Nov 2020