Opportunities and risks associated with identifying, sourcing and treating brackish groundwater

In the context of diminishing surface water availability and rising water costs in the Murray-Darling Basin, brackish groundwater represents a significant alternative water resource that could support irrigated agriculture and other water users to decouple from climate sensitive water sources. Motivations for the uptake of desalinated water in agricultural contexts include building resilience to cope with future changes in climatic and economic conditions (droughts, water market fluctuations), expanding production, and tailoring water quality parameters to specific agricultural needs. Despite desalination technologies being reasonably well established, farmers face various barriers to adopting this technology, including uncertainty over the implementation process, the availability of brackish water, the ability to dispose of desalination brine, implementation costs, and regulatory barriers. This work evaluates the conditions under which brackish groundwater could be used at scale. The primary objective has been to build an accessible knowledge base of resources for potential water users, such as farmers in the irrigated agriculture sector seeking to enhance drought resilience or expand production. This is being achieved through the development of an online brackish groundwater cost calculator, a detailed summary of brine disposal options, and the implementation of a field demonstration site. Innovatively, the demonstration site uses aquifer injection for brine disposal, rather than the more commonly used method of brine disposal via evaporation ponds. Extensive consultations with key First Nations, industry, government, and academic stakeholders have provided valuable insights into opportunities and barriers for future adoption. These findings are used to develop a future outlook for the broader adoption of brackish groundwater desalination, alongside other alternative water sources in the MDB. This approach aims to diversify water sources and enhance the Basin's resilience to future challenges.