Neil McDougall Lake


Like many other wetlands and lakes across the Perth metropolitan area, Neil McDougall Lake experiences an almost yearly reccurrence of a dense Lemna (duckweed) mat that covers the lake. Blue-green algae blooms are also noted at the Lake when naturally occurring blue-green algae multiply quickly and dominate the water column.

A sustainable solution

The City is investigating a long-term, sustainable solution for the management of the duckweed and blue-green algae blooms. 

The lake has significant environmental values and is visited by a variety of birds including the Western Swamp Hen, Pacific Black Duck, Eurasian Coot and Black Swan, as well as the Western long-necked tortoise, and the surrounding parkland is home to numerous passerines and small native Fauna.

Neil McDougall Lake acts as an infiltration basin and receives stormwater from four catchments, resulting in excess nutrients and organic loading entering the lake. High level of nutrients promotes algal blooms and low oxygen conditions, which in turn stress aquatic organisms. Other contaminants, such as heavy metals, also enter the lake through the drainage network and together with nutrients accumulate in the sediment. These can be released into the water column and enter the food chain.  

The lake is shallow and has no outflow to promote flushing. As such there is an insufficient water movement to disrupt the blue-green algae growth cycle or to allow fringing vegetation to filter and remove nutrients.

Poor water movement and stagnation also lead to high temperatures in the water column in summer, which is one of the main factors fostering algal blooms. 

An integrated remediation solution has been designed to address the processes driving the algae and duckweed blooms. This system addresses the continual inputs of polluted stormwater and poor lake circulation and is designed to operate with minimum maintenance requirements.

The system will also provide a range of additional benefits such as:

  • Biodiversity enhancement and increased resilience
  • Enhancement of the landscape and amenity values of the lake and surrounds
  • Provision for nesting and shelters for native birds and animals
  • Opportunities for environmental education.

Community consultation

In March 2019 the community were invited to provide feedback on the preliminary water sensitive urban design.

A feedback and outcomes report is available on Your Say South Perth. The design was updated taking on board the feedback along with the outcomes of environmental studies.

The design has now been finalised and design was completed mid 2020. 

In early 2021 the City secured funds from the Local Roads and Community Infrastructure Grant funding for implementation of the construction of stage 1. Stage 1 construction is anticipated to commence in early 2022 subject to procurement.


Related documents

Neil McDougall lake

Water project helps restore Neil McDougall Lake

Media Release 16 September 2022
Neil McDougall Lake Parks and Reserve works

Managing water quality and seasonal algal blooms at Neil McDougall Park in Como has long been a focus for the City of South Perth.

For decades, the park’s lake has been affected by algal blooms between October and March, which have been exacerbated by our drying climate and reduced rainfall.

The lake is also a receiving water body for stormwater and collects nutrients from the surrounding catchment area, which can promote outbreaks of blue-green algae.

The City’s Environmental, Construction and Natural Areas teams have worked closely with environmental experts and the local community to find solutions to improve the water quality at Neil McDougall Park.

With financial assistance from the Federal Government, the City has introduced a range of water sensitive urban design features to help reduce the level of nutrients before they enter the lake to reduce the extent of algal blooms.

Mayor Greg Milner said the restoration work at Neil McDougall Park would significantly enhance water quality, environmental health, habitat for native birdlife and improve the landscape of the surrounding areas.

“Phase 1 of the project off Ley Street is almost complete, with the creation of new wetland areas to filter water run-off, while the installation of circulation pumps and pollutant traps will help to improve water quality,” he said.

“Although the underlying works are significant in scope, they don’t interfere with the aesthetic appeal of this beautiful park. The new wetland areas sit naturally within the existing landscape, while delivering a range of tangible and demonstrable environmental benefits.”

The City worked with environmental services company Syrinx on many of the ‘unseen’ aspects of this project, which included a custom-designed litter trap to provide City staff with a quick and easy way to keep debris out of the new wetlands. 

Phase 2 of the project will involve similar restoration work at the Henley Street end of the park to be completed over the coming months.

The $1.3 million project has been largely funded through the Australian Government’s Local Roads and Community Infrastructure Program.

Please visit our Environment page to learn more about the City's environmental projects.


  • The City’s Construction Programs Coordinator Lewis Wise and Mayor Greg Milner view progress of the environmental works at Neil McDougall Park.
  • Custom-designed pollutant trap and extensive native planting are features of the new wetland 'filtration' area.

Contact us

For more information, please contact the City.