Onslow Desalination Plant

What's happening?

To secure Onslow's long-term water future, Water Corporation has started construction of a seawater desalination plant in Onslow. The plant will include:

• Reverse osmosis seawater desalination plant
• Intake and outfall pipeline(s) at Beadon Bay
• Water tank and pumping station
• A 2.5 kilometres-long belowground pipeline to the existing Onslow tanks, where the water will be connected to the town’s water supply.

Water Corporation awarded the contract to design and construct the Onslow Seawater Desalination Plant (OSDP) to Guidera O’Connor in August 2023.

In August 2024, Kimberley Civil and Drainage was awarded the contract to construct a new pipeline that will connect the future plant to the existing Onslow tanks. 

_{Artist’s impression of the future plant based on the engineering design at 60 per cent complete. The appearance of the plant will change as further progress is made on the design.}

Where is this happening?

The Onslow Seawater Desalination Plant will be built on the coastal side of Beadon Creek Road, between Bindi Bindi Aboriginal Community and Discovery Parks Onslow. 

When is this happening?

Early site works commenced in July 2024.

Plant and pipeline to tanks construction started in September 2024.

The OSDP is scheduled to produce water in 2026.

At this stage, construction of the ocean pipelines is expected to start in 2025. Further information will be provided closer to the time.

Why is this work taking place?

The desalination plant will provide a reliable drinking water source for Onslow, which is currently supplied by the Cane River Borefield.

The borefield requires rainfall to recharge and there is a trend towards a drying climate. A further 1.5 million litres per day of drinking water is needed to meet demand for the next 20 years.

The desalination plant will supply an additional, rainfall-independent drinking water source for Onslow. 

The plant will help meet future demand, which is expected to double by 2045 due to population and industry growth.

What consultation has occurred?

We have completed extensive investigations and community and stakeholder engagement on the desalination plant since 2019. We have engaged with stakeholders and members of the community to obtain feedback including:

• Government agencies and the Shire of Ashburton
• Adjacent landowners, occupiers and local industry
• Traditional owners
• Marine stakeholders
• the Onslow Chamber of Commerce and Industry, and
• the local community

Consultation has informed aspects of the plant, such as its location, and the method of pigging (removal of build-up in the marine pipelines).

Water Corporation referred the desalination plant proposal to the Environmental Protection Authority in January 2021. A public comment period occurred between 29 March and 7 April 2021. The regulator decided that the proposal would not be assessed under Part IV of the EP Act.

You can see the referral here.

We are committed to providing the local community with ongoing project updates

How will this project affect the community?

The desalination plant will be new infrastructure on the coast of Onslow. It will be minor compared with similar proposed desalination plants and is being designed to minimise environmental impacts.

Construction work can have local impacts, including noise, dust, traffic management and vibration. Before we start work in an area, we notify the surrounding community.

You may notice an increase in traffic accessing the site using the entrance off Beadon Creek Road. Traffic conditions may temporarily change during construction of the pipeline down McAullay Road.

The marine pipelines will be constructed below ground, and the community can access the beach area as normal when construction is complete. The location of the marine pipeline will be added to navigational charts for mariners.

Subtle vegetated buffers will be constructed on the Beadon Creek Road and Bindi Bindi Aboriginal Community sides of the plant.

Has Water Corporation investigated alternatives to the desalination plant?

We have considered various alternatives to the desalination plant. We investigated a Water Treatment Plant involving water from Birdrong Aquifer and deferred this option due to concerns about the source’s complexity and water quality.

Plans for a desalination plant with water sourced from Beadon Creek were also discontinued due to proximity to mangroves and salt production operations. We have also explored sourcing water from coastal bores, however the yield and water quality were inadequate. Ultimately, the Onslow Desalination Plant is the best option.

How is this project funded?

The project is funded by Chevron and the State Government of Western Australia.