Gnarabup wastewater planning

If progressed, the proposed pipeline will transfer wastewater from Gnarabup to Margaret River for treatment at the Margaret River Resource Recovery Facility, where 100% of the wastewater is re-used.

The pipeline will be located below ground, mostly within road verges, mainly along Wallcliffe Road. A proposed pipeline route map is available on this page. This route was chosen to help reduce environmental impacts and to minimise disruption to traffic during construction. 

 

We are currently completing investigations and design work to ensure the pipeline is a suitable option for the Gnarabup wastewater system, should an upgrade be required.

This work will help to determine the potential cost of the project. Funding arrangements would be considered with the State Government if a decision is made to proceed.

Decommissioning the existing Gnarabup Wastewater Treatment Plant (WWTP) is not part of the scope of the current stage of investigations. Our current focus is confirming whether constructing a new pipeline to Margaret River is a suitable option for wastewater upgrades, should it be required. If an upgrade proceeds in the future, including construction of a new pipeline, we could then consider the future of the existing WWTP. 

There is currently no decision to proceed with the project and no delivery timeframe has been set. We plan upgrades based on population forecast data and projected operational lifespan. Based on current forecasts, which do not include potential resort development, the existing WWTP is expected to continue meeting wastewater demand for the next decade, while continuing to operate in accordance with its environmental licence. 

We would only consider upgrading the wastewater scheme is future development proceeds and demand grows beyond current forecasts. Any decision to proceed would be subject to further planning, approvals and funding. 

Currently, Prevelly does not have reticulated sewerage. The WA Government's Infill Sewerage Program ended several years ago and extending sewerage services to Prevelly is not within the scope of the current project. However, the proposed upgrade design, including the size of the pressure pipeline and emergency storage tanks, considers potential future development scenarios, including any future changes to wastewater servicing requirements. 

The Gnarabup Wastewater Treatment Plant (WWTP) operates under strict environmental licence conditions set by the Department of Water and Environmental Regulation (DWER). 

We regularly monitor the plant's environmental performance, including groundwater quality before and after treatment, to ensure it continues to meet licence conditions. Monitoring results are reported to DWER as part of our ongoing compliance obligations.  

A range of environmental surveys and investigations have been completed along the proposed pipeline route to better understand local vegetation, habitat condition and the presence of significant species.
These studies included assessments of native vegetation and habitat used by species including western ringtail possums and black cockatoos. The findings have informed project planning and design, and have been used to support the environmental referral process.  

The project has been referred to the Australian Government under the Environment Protection and Biodiversity Conservation (EPBC) Act so potential environmental impacts can be independently assessed. Referring a project is a standard step in the planning process for projects in environmentally sensitive areas. It allows regulators to consider potential impacts and determine whether any further environmental assessment is required.

The referral includes environmental studies completed to date and considers the largest area that could potentially be affected during construction. This allows potential impacts to be identified and assessed at an early stage of planning and helps inform ways to avoid or reduce impacts where possible.

Environmental assessment processes can take time, which is why referrals are often submitted early while planning and design work continues. Referring a project does not mean a decision has been made to proceed. 

Yes, some vegetation clearing will be needed to construct the proposed pipeline. The environmental referral considers the largest area that could potentially be affected during construction. The final construction area is expected to be smaller and will continue to be refined as planning and design progresses. We are committed to avoiding and minimising environmental impacts wherever practicable.

Proposed measures include:

• refining the alignment to avoid sensitive environmental areas
• locating the pipeline within existing road reserves where practicable
• using underground horizontal drilling along significant sections of the route to reduce surface disturbance
• carefully planning construction methods, access requirements and work areas with input from environmental specialists, arborists and experienced contractors.

Where practicable, areas temporarily disturbed during construction would be rehabilitated following completion of the works, in consultation with the Shire of Augusta Margaret River.

We understand that construction can be disruptive, and we’re committed to working closely with the community to reduce any impacts as much as possible. If this potential project goes ahead, we will continue to engage with the community to better understand concerns around construction impacts and explore ways to minimise them – especially during peak tourist season and major events.

People living near the construction area may notice some noise, vibration, or dust. These impacts will vary depending on where you live, and the type of work being done. Water Corporation and its contractor will take steps to manage these impacts

The proposed pipeline is a pressure main that carries wastewater from homes and businesses to a treatment plant or recovery facility. The wastewater is pushed through the pipe using pumps, which helps move it uphill or over long distances where gravity alone wouldn’t work.

There are no household or businesses sewer connections on the wastewater pressure main. Your existing connection to our wastewater system will not be impacted.

If the proposed pipeline goes ahead:

• A detailed traffic plan will be developed by the contractors and approved by the Shire of Augusta Margaret River.
• The plan will maintain public access and make sure people can still get around safely.
• We’ll share this plan with the community, so you know what to expect.
• We’ll make sure you can still access your property during construction.

We recently provided further information on the proposed pump station upgrade to answer further queries from residents who live nearby. The Information Sheet on the proposed pump station upgrade is included on this page.

We recently shared with the community our progress of planning for an upgrade to the Gnarabup wastewater scheme, should it be needed. Our team held three drop-in sessions across Friday 12 September and Saturday 13 September 2025, to discuss the upgrade options.

We really appreciate meeting so many of you and the opportunity to hear your thoughts, and answer your questions. Your input helps us better understand what matters most to you as we move forward with our investigations and planning.

The opportunity to provide comments and ask questions is always open. Please get in touch using the contact details on the webpage and we would be happy to provide further information.

We have been assessing a number of options to upgrade the Gnarabup wastewater scheme, should it be required.

Our preferred option is to build a new approximately 10km pipeline to move all wastewater from Gnarabup to Margaret River for treatment. A map of the proposed pipeline route is included on this page.

To move wastewater in the proposed pipeline an upgrade of our pump station at Chuditch Place would be needed.

Planning wastewater upgrades takes time. We will continue investigating the viability of the pipeline option, should an upgrade be needed in the future.