Water for the Future: Perth and South-West WA

The south-west of Western Australia is getting drier, population growth is continuing and additional water supply options for the south-west of the state are high on everyone’s agenda. The Water for a Healthy Country Flagship and the West Australian Government have completed a major study that outlines demand and supply options for Perth’s future. 

The south-west of WA has been impacted by climate change as extensively as any part of the world. Rainfall is 10-15% lower than it was 30 years ago and inflow into local dams has halved in the same period. At the same time, the demand for water to meet industrial, agricultural and domestic growth is doubling every 15 years and urban population growth is 1.8% per annum. 

The Water for a Healthy Country Flagship in partnership with the Office of Water Strategy, WA Department of Environment and Water Corporation have completed a ‘whole of system’ review of existing and potential water resources for south-west WA. The systems based analysis included likely public and private demand; projected levels of water allocation and extraction; costs of delivery from each scheme source, opportunities for planning controls, sustainability considerations and the likely impact of climate change. 

This information is now supporting the work of the Expert Panel examining Kimberley water as a supply option for Perth and investment in the Integrated Water Supply Scheme, ensuring Perth’s development and ability to cater for a population now exceeding 1.4M.

The main findings were: 

• Groundwater resources under the Perth Basin are still not fully exploited, even given the need to reduce yields due to the drier climate and to uncertainties about the impact of current extraction and increased future demand from private users

• The demand for water in the Perth areas has exceeded the ability of the nearby region to supply it and increasingly, water will be required from more distant sources or desalination. The most prospective of these are deep groundwater reserves in the south-west of the Perth Basin where sustainable yields are currently set at a conservative level. 
• We need to substantially increase our knowledge of groundwater resources and the impacts of development to match the level of exploitation. It will also help the orderly development of the next most appropriate new resource rather than the one that can meet an urgent demand by a certain timeframe.  
• The inter-connected nature of the many water sources used to supply the Integrated Water Supply Scheme provides the region with a resilience that has helped adapt to climate change and to rapid development with a relatively minor impact. Currently there are four main water sources – shallow unconfined aquifers, confined aquifers, surface dams and desalination. These are linked across a network that extends over 600km east-west and over 200 km south-north allowing sources to be substituted if they fail for any reason. 
• There remains scope for increased demand management and for reuse of treated wastewater that is currently discharged into the Indian Ocean.  There is also scope for improving the management of both surface and groundwater catchments to improve water yields and, in some cases, nature conservation values.  Managed Aquifer recharge is likely to be a key part of the solution especially with Perth’s sandy aquifers. 
• The right mix of new sources, demand management, reuse and catchment management requires a framework for objective decision making. Integrated Resource Planning is recommended in the State Water Strategy to allow these options to be compared. 

Next steps: The Flagship is assisting the state government and Water Corporation to build an end use model for the Integrated Water Supply Scheme so that all options can be compared in an objective framework.

SW Western Australia Selected Water Opportunities

Read the full report - Context Report on South West Water Resources

For more information contact:
Dr Don McFarlane
Ph: +61 8 8933 6215
don.mcfarlane@csiro.au

Read more about the Flagship’s research in Western Australia at

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