Desalination plant at Billy Lights Point

As we proceed with work to deliver a desalination plant at Billy Lights Point, ensuring long-term water security for the Eyre Peninsula, we will provide regular project updates through the detailed design, development application preparation, approvals, and construction processes.

Read the project update.

Billy Lights Point is our preferred location

Our proposed site at Billy Lights Point is:

• close to existing water and electricity networks, requiring a short, 4 km powerline route and a 7.4 km transfer main to North Side Hill storage tanks
• formerly industrial and not located near residential properties, which will help to minimise visual and environmental impact on the landscape
• relatively sheltered with a mostly flat landscape, helping to reduce construction risks and challenges, delivering the best value option for our customers.

A number of alternative locations have been assessed and investigated for the Eyre Peninsula desalination plant, however, these presented challenges including:

• nationally and state protected flora and fauna
• internationally and nationally protected species such as migratory whales
• location within or adjacent to a State Marine Park
• unique geology
• high cliffs and exposed coastline requiring significant engineering design and complex construction processes, resulting in an additional $150 million cost impost on customers.

Billy Lights Point is our preferred location because it offers the quickest solution to ensuring long-term water security for the region, with the least impact on future water costs for customers. Marine science research undertaken to date indicates that with the right engineering design, a desalination plant at Billy Lights Point can be built with minimal impact on the marine and coastal environments.

Concept design image for the Eyre Peninsula desalination plant. Final design to be confirmed.

First water expected mid-2026

By mid-2026, a desalination plant at Billy Lights Point would produce 0.016 gigalitres or 16 megalitres of fresh, clean drinking water per day – with the capacity to be expanded to around 0.024 gigalitres or 24 megalitres per day.

Further scientific investigations and assessments will inform the detailed design of the plant, including the location of the intake (where the plant draws in seawater) and outfall (where the plant disperses saline concentrate from the desalination process) pipes.

The data from these investigations and assessments, along with community input, informed our development application for the project, which was lodged with the State Planning Commission in June 2024. Our application is being assessed by multiple agencies and regulators through a comprehensive approval process, which provided for further community consultation.

How desalination works

1. Pre-treatment - seawater is pumped through intake screens and filters to remove particles, before passing through an ultrafiltration membrane.
2. Reverse osmosis - semi-permeable membranes allow water molecules to pass through but block larger salt molecules, resulting in the removal of impurities and salt in the water.
3. Post-treatment - the desalinated water is disinfected and re-mineralised to increase alkalinity to reduce the potential for corrosion in the network and customers’ plumbing. Treated water meets the Australian Drinking Water Guidelines, ensuring it is safe to drink.
4. Storage - the clean drinking water is then stored and supplied to homes and businesses.
5. Outfall - the remaining concentrated seawater is returned to the ocean through the outfall pipe and diffusers to ensure it reaches the natural salinity levels of the environment.
   
   

After desalination, clean, fresh water from the desalination plant would be pumped to the North Side Hill storage tanks near Port Lincoln. The water would then be distributed through our network to ensure it reaches regional and remote communities across the Eyre Peninsula, for use in homes, schools, hospitals, businesses, and agriculture.

Eyre Peninsula’s water security challenges

The research

The proposed desalination plant requires a licence to operate from the Environment Protection Authority (EPA), which will only be granted if the plant can meet strict conditions assessed against ongoing monitoring of the local marine environment, including through construction and operation stages. Any discharge (including of chemicals associated with the desalination process) from the plant also needs to meet EPA requirements, and approval will only be granted if we can show that the discharge poses no risk to the receiving environment.

Any chemicals discharged from the desalination plant will be neutralised and many are already present in seawater, with the exception of anti-scalant. Anti-scalant is used to clean reverse osmosis membranes and is commonly used and approved across Australia for discharge from desalination plants into marine environments.

The marine environment of Boston and Proper Bays, off the coast of Billy Lights Point, has been continuously monitored and modelled since September 2021, with research findings peer-reviewed and validated by an independent Marine Science Review Panel consisting of internationally recognised experts.

Marine Science Review Panel

In 2022, the panel reviewed the following marine science reports:

• Oceanographic monitoring and far-field modelling to inform desalination in Boston Bay – Dr Mark Doubell and Dr Charles James, SARDI
• Marine Characterisation of Water Quality at Billy Lights Point and Point Boston, Port Lincoln – James Paterson, SA Water
• Desalination Ecotoxicity Review – Dr Andy Markham and Dr Ross Smith, Hydrobiology
• Boston Bay Marine Habitat Video Analysis – James Brook, J Diversity Pty Ltd

The panel supported the research outcomes and recommendations, and advised that a desalination plant at Billy Lights Point can be constructed and operated without negatively impacting the marine environment if the intake and outfall structures are designed to the existing marine conditions.

The Marine Science Review Panel will continue to provide specialist advice throughout the detailed design and development application phase of the project, and through the establishment of operational monitoring programs.

SARDI far-field modelling

Using a five-year model hindcast, the South Australian Research and Development Institute (SARDI) modelled predictions of the far-field salinity differences between a 12 GL per year desalination plant operating at full capacity and a model simulation with no desalination. The model showed a maximum seasonally-averaged salinity anomaly of 0.44 PSU within 250 to 500 metres of outfalls. This anomaly is equivalent to a 1.2 per cent change in the ambient salinity. Maximum seasonally-averaged anomalies were reduced to less than 0.1 PSU (equivalent to less than 0.3 per cent change in the ambient salinity) at distances greater than 1 km from outfalls. Modelling a 12 GL per year desalination plant was an ultraconservative approach, as this is more than double the initial capacity of 5.3 GL per year and 50 per cent larger than the proposed 8 GL per year ultimate capacity of the plant.

This animation of the 5-year hindcast model shows daily bottom salinity distributions for model scenarios with and without desalination, and at each outfall location.

S0 = no desalination plant — BL = Billy Lights Point — BLX = Billy Lights Point extended outfall
PB = Point Boston — PBX = Point Boston extended outfall — CD = Cape Donington.

Salinity levels

The wider potential impacts on salinity in Boston and Proper Bays from the long-term operation of the desalination plant have been modelled by SARDI. Tidal data shows saline discharge falling well within natural background salinity levels after mixing, and therefore remaining well below the ANZECC & ARMCANZ water quality guidelines relating to changes in salinity.

Modelling of the diffuser’s near- and far-field discharge zones will continue during detailed design, construction, and operation. Validation monitoring and reporting to regulators to ensure key environmental criteria are met would form part of our licence conditions.

Through considered design of discharge diffusers, pipeline length, and outfall location, the desalination plant at Billy Lights Point would meet the minimum dilution standard by the time saline discharge meets the seabed under all conditions, including dodge tides.

Impact on mussel spat from intake

Mussels are broadcast spawners, with millions of larvae released by the female. Extraction of water by any marine system will remove particles, including larvae and spat. This currently occurs with various existing operations in Boston and Proper Bays drawing in seawater and, to date, there has been no known impact on mussel production and farming.

During the detailed design phase, habitat mapping studies and particle tracking modelling will help to identify which areas are more sensitive in relation to the intake pipe. At Billy Lights Point, fewer than 0.1 per cent of the particles in the water, such as larvae, are at risk of coming within a 25m zone around the intake pipe.

As the design for the plant progresses, we will continue to work with industry and marine specialists to optimise the intake location and ensure it is not located adjacent to an area where large numbers of mussels are likely to occur.

In our conversations with the community, we are frequently asked questions such as:

• Why do we need a desalination plant?
• Why wasn’t the Site Selection Committee’s recommendation of Sleaford West accepted?
• Will the intake pull in fish and mussels like a vacuum cleaner?

Find the answers to these questions and more on our frequently asked questions page.