Rockingham and Mandurah area odours

The Department of Water and Environmental Regulation has received and is investigating an increase in odour complaints from residents in the Rockingham and Mandurah area.
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The Department of Water and Environmental Regulation (the department) is carrying out odour surveys in the south portion of the City of Rockingham (Secret Harbour and Golden Bay area) and Mandurah area, including Singleton, Lakelands and surrounding suburbs. 

Surveys across local licensed facilities (e.g. wastewater treatment plants, waste transfer stations, landfills, composting operations and piggeries), as well as several natural sources of odour including Black Swan Lake, Goegrup Lake and sections of the Serpentine River with potential to contribute to odour emissions, are being investigated.

The outcome of the odour surveys and inspections will inform any further investigations. 

The department undertook a previous risk-based review of licences held by WA Composts Pty Ltd (L8410) (known as C-Wise), Mushroom Exchange Pty Ltd (L7210) and Derby Industries Pty Ltd (L6932) (known as CM Farms), and in 2018 each licence was amended to include additional conditions relating to controls for odour and waste acceptance, storage and management.

The department is continuing to work with the licence holders to ensure conditions of the amended licences are complied with and operational controls remain sufficient to mitigate odour. These controls are being assessed as part of ongoing inspections of these licensed premises.

Investigations suggest that there are several natural sources of odour contributing to the odours being experienced in the area. These natural odours are likely caused by the reduced inflow of water into the lake and river system following a drier-than-average winter period coupled with warmer-than-average summer temperatures. This natural process results in organic matter on the lake floor and riverbanks being exposed to the air and sun, causing it to break down (oxidise). This process can release sulphurous odours, often described as ‘rotten egg smell’.

What is happening now?

The department is currently investigating a significant increase of odour complaints received from the community in the Nambeelup area in 2024. 

The department takes odour complaints seriously and understands that odour can cause significant impacts on communities.  

The department responded quickly to community complaints and has conducted extensive field odour surveys, both during the day and at night. During surveys on 15 and 16 February 2024, the department identified the activities of two companies in Nambeelup (C-Wise and CM Farms) to be the primary sources of the odours identified in the community.

C-Wise accepts liquid waste and produces compost, while CM Farms operates a piggery.

Following discussions with both parties, the department issued an Environmental Protection Notice (EPN) to each company requiring them to investigate the identified odour and rectify any identified operational issues as quickly as possible.

C-Wise is required to:

  • take immediate action to reduce the risk of odour emissions from the liquid waste storage and treatment ponds
  • conduct investigations into liquid waste storage and treatment ponds at the premises to ensure effective control of odour emissions from the ponds
  • engage an odour expert to conduct an odour analysis considering all waste types received at the premises
  • comply with required timeframes, considerations and reporting requirements set out in the EPN, and provide details of any improvements that can be made to operations on the premises to reduce unreasonable odour emissions.

View the C-Wise EPN.

CM Farms is required to:

  • engage a wastewater expert to undertake an investigation into the performance of the wastewater treatment ponds on the premises and provide details of factors that are likely to be contributing to the unreasonable odour emissions from the ponds
  • identify any improvements to the wastewater treatment plant and wastewater treatment ponds necessary to reduce the potential for unreasonable odour emissions
  • comply with required timeframes, considerations and reporting requirements set out in the EPN for assessing the performance of the ponds.

View the CM Farms EPN.

The businesses are required to provide preliminary investigation results within 14 days of the issuing of the EPN.

The department is grateful for community reporting of ongoing odour impacts as it aids the investigation and identification of odour sources. 

Community members and residents are reminded that it is important to report odour impacts at the time that they occur by calling the Pollution Watch Hotline on 1300 784 782. The online reporting tool can be used to lodge complaints after the impact has occurred.

More information

This page will be updated as new information becomes available. If you have any questions relating to this issue, please email