| Key Points |
|
The River Murray is flowing under growing climate strain, and what happens to its water will shape the future of inland south-eastern Australia.[3]
Stretching across Queensland, New South Wales, the Australian Capital Territory, Victoria and South Australia, it anchors the wider Murray–Darling Basin, which covers about one seventh of the continent.[1]
More than two million people rely directly on Murray water for drinking, farming and industry, while many more depend on basin food and fibre exports.[2]
The river is also central to the cultures and economies of dozens of First Nations who know it as Murrundi and other names, and who regard flowing water as a living ancestor rather than a commodity.[4]
Over the past two decades, climate change, over-extraction and prolonged drought have exposed how fragile this system can be, from choking algal blooms to the ecological trauma of the Millennium Drought and the fish kills at Menindee.[3]
Governments have responded with the Murray–Darling Basin Plan, which aims to return more water to the river, but the Plan is now being tested by a hotter, drier and more volatile climate.[5]
As the Basin Plan approaches key review points and climate projections harden, the River Murray has become a frontline test of whether Australia can share a shrinking resource fairly while keeping a vast river system alive.[6]
Scale, shape and character of a working river
The River Murray is Australia's longest river, flowing for about 2,508 kilometres from its headwaters in the Australian Alps of New South Wales and Victoria to the Murray Mouth at the Coorong in South Australia.[1]
It is part of the Murray–Darling Basin, an inland catchment of roughly one million square kilometres that collects water from mostly semi-arid landscapes before delivering it through locks, weirs and barrages to the Southern Ocean.[1]
The river's natural flow once rose and fell with the seasons, with snowmelt and winter–spring rain driving high flows and periodic floodplain inundation, and hot summers bringing reduced baseflows.[1]
Over the past century, large dams, storages and more than a dozen weirs have reshaped those rhythms, smoothing peaks and boosting reliability for irrigation, navigation and urban supply at the cost of reduced flood frequency and altered habitat.[5]
At its lower end, the system fans out into the Lower Lakes and Coorong, a complex of freshwater and estuarine wetlands where the balance between river inflows, tides and evaporation is tightly managed through barrages.[5]
Salinity is a constant management challenge, as clearing, irrigation and reduced flows mobilise ancient salts in soils and groundwater, threatening crops, infrastructure and the health of river red gum floodplains.[5]
Economic engine, ecological lifeline, cultural home
The River Murray underpins one of Australia's most productive food bowls, supporting irrigated industries such as cotton, rice, grapes, citrus, almonds, dairy and horticulture worth several billion dollars a year in gross value.[2]
The river and its storages supply drinking water to inland centres including Adelaide, regional cities such as Mildura and Albury–Wodonga, and countless smaller communities along its length.[2]
Tourism, recreation and houseboat industries also rely on Murray flows, drawing visitors to fishing grounds, wetlands, national parks and riverside towns in all three downstream states.[2]
Ecologically, the Murray supports internationally recognised wetlands such as the Barmah–Millewa Forest, Chowilla Floodplain, Hattah Lakes and the Coorong and Lakes Alexandrina and Albert Ramsar sites, which provide habitat for waterbirds, native fish and floodplain forests.[5]
Many of these ecosystems depend on periodic overbank floods that recharge billabongs, wetlands and groundwater, disperse nutrients and trigger fish breeding and bird nesting events.[14]
When these floods are too rare or too small because of extractions and climate change, river red gums stress, black box woodlands thin, and native fish and bird populations decline.[5]
For First Nations across the basin, including the Ngarrindjeri at the Murray Mouth and the First Peoples of the River Murray and Mallee in South Australia, the river is a cultural landscape embedded in creation stories, law, ceremony and day-to-day subsistence.[4]
Traditional Owners have long argued that "cultural flows" – water entitlements owned and managed by Indigenous nations to sustain cultural, spiritual and economic values – must sit alongside environmental and consumptive uses in basin planning.[15]
Climate change, extremes and water quality stress
Australia has already warmed by about 1.5 degrees since 1910, and this has intensified heatwaves, increased evaporation and altered rainfall patterns over the Murray–Darling Basin.[13]
CSIRO and Bureau of Meteorology analyses show significant declines in cool-season rainfall and streamflows in the southern basin, with roughly one third of gauges recording reduced annual flows and fewer days of high flows.[13]
For the Murray, this means less reliable runoff from key catchments, more frequent low flows and a greater reliance on large storages to buffer years of drought.[10]
Climate modelling for the Basin suggests that a 5 percent drop in average annual rainfall by mid-century could translate into around a 20 percent reduction in average runoff, amplifying pressure on allocations even in non-drought years.[10]
Hotter, drier periods increase the risk of blue-green algal blooms, hypoxic "blackwater" events and fish kills, as low flows, warm water and high nutrient loads deplete oxygen and stress aquatic life.[16]
The 2018–19 Menindee fish kills in the Darling–Baaka and subsequent blackwater episodes downstream highlighted how compounded stresses from drought, over-extraction and extreme heat can push river ecosystems past tipping points.[13]
Conversely, climate change is also associated with more intense rainfall events, and the 2022–23 River Murray high flow was the second highest on record, delivering major ecological benefits but also widespread flooding and water quality risks.[16]
These extremes create management dilemmas, because operators must juggle flood mitigation, environmental outcomes and consumptive supply in a system with finite storage and rapidly changing inflows.[19]
Who gets the water, and how is it changing?
Water in the Murray is governed under the Murray–Darling Basin Plan, agreed in 2012 under the Commonwealth Water Act and implemented through state water resource plans, water sharing rules and a cap on overall diversions.[17]
The Plan sets a sustainable diversion limit and has recovered more than 2,100 gigalitres of water entitlements across the basin for environmental use, largely through buybacks and irrigation efficiency projects.[17]
Commonwealth and state environmental water holders now coordinate releases to mimic aspects of natural flow regimes, targeting key wetlands, floodplains and channel habitats along the Murray and its tributaries.[14]
Evaluation by South Australian agencies suggests that environmental watering has improved connectivity, water quality and habitat condition in many Murray floodplain and wetland assets, even as broader pressures persist.[11]
At the same time, irrigators, towns and industries continue to depend heavily on reliable allocations, and water markets allow entitlements and temporary allocations to be traded across regions and sectors.[17]
During droughts, high-security entitlements and critical human needs, including basic town water supplies and certain cultural and environmental requirements, are prioritised, but low-security users can face severe allocation cuts.[17]
First Nations groups have secured only a small fraction of basin water entitlements despite their recognised rights and interests, and many are calling for dedicated cultural water allocations in future Basin Plan reforms.[18]
Groundwater is an often overlooked part of the picture, yet studies point to falling levels in several major alluvial systems under both extraction and climate change, with implications for baseflows and long-term reliability.[19]
Future water security and what must happen next
Climate projections for south-eastern Australia point towards a future of higher temperatures, more frequent hot and dry years, shorter and sharper floods, and increasing evaporation losses from storages and floodplains.[13]
For the River Murray, this means the historical record is no longer a safe guide, and planners must stress-test water sharing rules, infrastructure and environmental watering programs against more extreme scenarios.[10]
Analyses underpinning the Basin Plan review process emphasise that current diversion limits and recovery targets may not be enough to protect key ecological assets and water quality under mid- to high-emissions climate pathways.[19]
Regional planners will need to consider more ambitious water recovery, smarter use of constraints relaxation to deliver overbank flows, and closer integration of surface water and groundwater management.[11]
They will also have to grapple with difficult questions about land use, such as whether some high-water-demand crops and marginal irrigation areas will remain viable under tighter limits and more volatile allocations.[17]
For policymakers, the challenge is to align climate mitigation, adaptation and water policy, ensuring that basin communities, First Nations and ecosystems are not left to absorb the costs of deferred decisions.[18]
That will require firm national emissions cuts to reduce long-term warming, robust funding for adaptation and river restoration, and genuine power-sharing with Traditional Owners over how water is owned, governed and used.[13]
If governments treat the River Murray as a barometer of climate readiness, rather than a reservoir to be exhausted, the choices made this decade can still bend the system towards a more resilient and just future.[6]
What regional planners and policymakers must focus on
Regional planners now face a narrowing climate window and must prioritise rigorous climate modelling, transparent trade-offs and scenario planning that acknowledges declining average flows and more volatile extremes.[10]
They need to update land-use and settlement strategies so that new housing, irrigation expansion and industrial growth occur in locations with secure, climate-robust water sources rather than in already stressed reaches.[19]
Policymakers must ensure the next Basin Plan review strengthens, rather than weakens, sustainable diversion limits, and that environmental water portfolios are large and flexible enough to maintain key ecological functions under harsher conditions.[11]
Embedding Indigenous water rights, co-governance and cultural flows in legislation and planning will be essential for both justice and resilience, because Traditional Owner knowledge offers locally grounded insight into how rivers respond to change.[18]
Targeted investment in demand management, efficient urban and agricultural use, and nature-based solutions such as wetland restoration can buy critical time as climate impacts intensify.[14]
Above all, the River Murray forces a clear choice on governments: whether to plan early for a future with less water, or to wait for the next crisis and again discover the costs of treating climate risk as tomorrow's problem.[6]
References
- Murray–Darling Basin Authority – Rivers of the Basin
- Murray–Darling Basin Authority – Basin economy and communities
- CSIRO & Bureau of Meteorology – Australia's changing climate
- South Australian Government – Traditional Owners of the SA River Murray
- South Australian Government – Basin Plan and environmental outcomes for the River Murray, Lower Lakes and Coorong
- Productivity Commission – Murray–Darling Basin Plan Review submissions
- South Australia State of the Environment – River Murray environmental challenges
- South Australian Government – Basin Plan monitoring and evaluation
- CSIRO & Bureau of Meteorology – State of the Climate
- Commonwealth Environmental Water Holder – Flow-MER program
- AIATSIS – Cultural flows in Murray River Country
- Goyder Institute – 2022–23 River Murray high flow environmental response
- National Irrigators' Council – Murray–Darling Basin Plan overview
- Australian Human Rights Commission – Water and Indigenous rights in the Murray–Darling Basin
- CSIRO – Submission to the Murray–Darling Basin Plan Review 2023