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Worker at the Lower Molonglo Quality Control Centre

Lower Molonglo Water Quality Control Centre (LMWQCC)

Icon Water owns and operates water and wastewater services to the Australian Capital Territory (ACT). The Lower Molonglo Water Quality Control Centre (LMWQCC) is the ACT’s main wastewater treatment plant and is the largest inland treatment facility in Australia. 





The cycle of sewage

Sewage is treated and released into the Molonglo River. It then flows into the Murrumbidgee River and drains into the Murray-Darling Basin river system, ultimately discharging into the ocean south of Adelaide. Water leaving this plant has been thoroughly treated, so it returns to the natural water cycle free of pollution and can be reused by other towns further downstream.



The process

The process includes physical, chemical, and biological treatment processes before the water is discharged into the Molonglo River.



Protecting our environment

LMWQCC’s treatment process ensures that water discharged into the Molonglo River will not affect the environment. Treated water from LMWQCC plays an important role in keeping local rivers flowing and supporting aquatic life— especially during dry periods— and reducing algae growth.

During dry periods, treated water from LMWQCC can provide up to 100% of the total flow of the Molonglo and Murrumbidgee Rivers. Due to this significant contribution to local river systems, maintaining water quality and the effectiveness of the treatment processes is a high priority.

We undertake extensive water quality monitoring and ecological monitoring to ensure that we have minimal impacts on the environment. Our Fish Monitoring Program and the levels of macro invertebrates—such as small crustaceans and insects—provides information on the river's health.




Treated water is recycled on-site for process cleaning, cooling, scrubbing and irrigation. It is also supplied off-site to a local golf course. 

Treated sewage solids such as sludge, screenings and grit are incinerated to make an ash. 

This ash is used as a soil conditioner called Agri-Ash. As it contains a large amount of lime, Agri-Ash can be applied to land in NSW as a liming material under the Resource Recovery Order issued by the NSW EPA under the Protection of the Environment Operations (Waste) Regulation 2014.

These are also a number of water reuse projects operating within the ACT, which treat wastewater for reuse in the irrigation of parks, playing fields and golf courses.



Effluent discharge targets

LMWQCC meets the following effluent discharge targets to ensure that treated water will not be harmful to the environment. Treated water leaving the plant contains less than: 

  • 550mg of total dissolved solids per litre 
  • 0.4mg of total phosphorus per litre 
  • 2,100 kilograms per day total nitrogen average daily load limit 
  • 10mg of suspended solids per litre 
  • 1.6−7.4mg of ammonia per litre, depending on the season 
  • 0.2mg total chlorine per litre 
  • 200 thermotolerant coliforms per 100 millilitres.




LMWQCC operates subject to an Environmental Authorisation issued by the ACT Environmental Protection Authority (EPA) under the ACT Environment Protection Act 1997 (ACT). Performance results are reported to the EPA monthly.




In line with Icon Water's commitment to ecological sustainability, LMWQCC has developed an Environmental Management Program. LMWQCC was the first sewage treatment facility in Australia to gain certification for the following International Standards:

  • AS/NZS ISO 9002 - Quality Management Systems
  • AS/NZS ISO 14001 - Environmental Management Systems




LMWQCC was built in the 1970s and cost $50 million to build at the time. It would cost $800 million to build a similar treatment plant today. 

The storage dam can hold up to 147 million litres of wastewater. 

Each day the plant:

  • treats 80 to 90 million litres of wastewater
  • recycles an average of 10 million litres of wastewater 
  • removes approximately 1 million litres of sludge from the process for dewatering and incineration 
  • produces approximately 16 tonnes of Agri-Ash.