Mandurah area odours

Latest updates

Odour issues continue to affect communities around Mandurah. The department has taken regulatory action and remains committed to resolving the issue.

Three licensed premises in Nambeelup operate under the Environmental Protection Act and are required to manage odour emissions:

• C-Wise (L8410/2009/2) – liquid waste, compost manufacturing and soil blending. Licence expires 22 April 2028.
• CM Farms (L6932/1988/11) – intensive piggery. Licence expires 26 Oct 2029.
• Mushroom Exchange (L7210/1997/10) – compost manufacturing and soil blending. Licence expires 27 Apr 2026.

The department is engaging with the businesses on investigations and expert assessments to decide actions are required to mitigate odour emissions from the precinct.

The department acknowledges the investigations have been lengthy, but the issue is very complex due to multiple odour sources and takes time to fully address. The department aims to keep the community informed through prompt and reliable updates to this community page. Please check here regularly for the latest news. 

The department continues to assess the odour within the area and is using a number of techniques, including;

• Odour field surveys (OFS) which involve field teams following strict protocols to identify odours using the most reliable equipment available (the human nose).
• Chemical monitoring equipment including handheld gas meters, sensors and remote sensing infra-red monitors for specialised compounds. This equipment can detect chemicals that are associated with odour under some circumstances and can be useful for detecting chemical indicators from activities that are producing odour.
• On 12 November 2025, the department met with community representatives who will be assisting in an odour diary sentinel program in Mandurah and the surrounding areas. This program will allow residents to log their odour experiences with greater detail. The department is grateful to the community members who have volunteered to be involved in this program which will help us to verify the conditions contributing to odour impacts and monitor the effectiveness of improvements as they occur across the precinct.

C-Wise

On 12 December 2025, the department amended the C-Wise operating licence (L8410/2009/2) to incorporate a number of improvements on the premises as regulatory requirements. These include:

• Stronger odour planning, monitoring and investigations through implementation of a summer odour contingency plan, update of the site’s existing odour plan, commissioning of independent investigations into pond wastewater, and continuous monitoring with trigger actions.
• Infrastructure and operational upgrades including installation of new sumps, tanks and hardstands, rapid cover of animal mortalities, and planning for the enclosure or roofing of mortality composting and other key areas.
• Pond treatments and compliance actions including undertaking a range of pond odour reduction trials, implementation of a comprehensive sludge and sediment management plan, and rapid notification to DWER of non-standard activities.

The department is holding fortnightly meetings with C-Wise to review their action plan to address odour emissions and to ensure progress is being made.

C-Wise has initiated many of the investigations, planning processes, odour reduction trials and operational improvements which are now captured in the licence amendment.

C-Wise has also made several improvements including proactively reducing waste acceptance during winter to support operations to mitigate odour, and the company is investigating other improvements, including a proposed change to the ponds to better manage wastewater.

Any change to current operations will be assessed by the department to ensure the changes are appropriate.

CM Farms

On 13 November 2025, the department amended the CM Farms licence to require infrastructure upgrades and the implementation of operational improvements aimed at reducing the potential for off-site odours. The Licence now mandates the development of a sludge management plan, including strategies to minimise sludge accumulation in wastewater treatment ponds and to ensure sludge storage and removal practices that minimise odours and environmental impacts. Additionally, the licence requires increased pond monitoring and reporting requirements.

The most recent licence amendment and Amendment Report – Granted 13 November 2025 can be found on the department web page CM Farms Licence (L6932/1988/1).

Background

Throughout 2024 and 2025 to date, the department has received a high volume of odour complaints from residents in Secret Harbour, Mandurah, Singleton and Lakelands.

Following investigations which identified several businesses in Nambeelup as potential sources of these emissions, the department issued Environmental Protection Notices (EPNs) on 22 February 2024 to:

• WA Composts Pty Ltd (C-Wise) – C-Wise EPN (now completed and revoked).
• Derby Industries Pty Ltd (CM Farms) – CM Farms EPN.

Odour and wastewater experts were engaged to support ongoing assessments and recommend actions to reduce emissions.

On 25 October 2024, the department amended C-Wise’s licence to introduce stricter odour control conditions, including a requirement to develop a sludge management plan addressing odour, leachate and PFAS compliance.

The department engaged an odour expert in late 2024 to better understand the odour emissions and inform further operational improvements.

Additional odour surveys were conducted in 2025 to assist the odour expert’s assessment, based on community complaints.

More recently, the department engaged an independent consultant to collect samples across the Nambeelup precinct for a current analysis of all ponds and composting material. The information obtained from the consultation is further assisting in the assessment and identification of areas for improvement to mitigate odours. 

Working together

The department is grateful for community reporting of ongoing odour impacts, which supports the investigation and identification of odour sources. While some people may be weary of informing the department of the odour, the information is crucial to understanding the impact any changes to site operations may be having on community amenity.

Community members and residents are reminded that it is important to report odour impacts at the time odour is occurring by calling the Environment WAtch Hotline on 1300 784 782 or using the online reporting tool. Please be as specific as possible when describing the odour and its impact.

If you are concerned about your health, please see your doctor or call Health Direct on 1800 022 222 to discuss your symptoms.

We recognise and respect the right of individuals to express their views but we ask the community to respect the safety of our staff, contractors and visitors while we work to resolve these odour issues. We appreciate the community’s cooperation in maintaining a safe and constructive environment for everyone.

This page will be updated as new information becomes available. If you have any questions relating to this issue, please call the Environment WAtch Hotline on 1300 784 782.