Masterplan Implementation Update

The following information provides an update on the progress of implementing the Maylands Lakes Environmental Restoration Masterplan.

Application of Phoslock and EarthTec algaecide

A key action in the plan is the application of Phoslock in Lakes Brearley and Bungana. This treatment is designed to reduce the amount of bioavailable phosphorus in the water column and sediment. Applying this product is expected to improve the overall water quality and reduce the concentration of blue-green algae in these lakes over time. A contractor has been appointed, with the application to commence in March and be completed by early April.

A bathymetric survey of the lakes was undertaken to ensure the accuracy and effectiveness of the proposed treatment. This provided precise data on lake depths, sediment profiles and total water volume, which are critical inputs for calculating the correct Phoslock dosing rates and distribution methodology. This information enabled the calculation of the dosing rates to be applied by the contractor to specific sections of the lakes.

Lake Brearley is currently experiencing an algal bloom, whereas Lake Bungana is not exhibiting bloom conditions. The effectiveness of Phoslock is reduced when there is a significant algal bloom already underway. Phoslock functions as a phosphorus binder; it is, however, not an algaecide. While it removes the nutrient source that fuels future blooms, an existing and substantial algal population can continue to persist on nutrients already stored within its biomass. In addition, a large bloom can overwhelm or interfere with the product’s binding mechanism, significantly impacting its effectiveness in reducing phosphorus concentrations within the waterbody.

To address this, the City’s consultants propose the use of a product called EarthTec to release any phosphorus bound in algal cells prior to the application of Phoslock. This product is different from more traditional copper sulphate algaecides primarily because it is a fully dissolved, ionic copper formulation that remains suspended in the water column and is controlled by biological demand rather than water conditions. Available information indicates it is typically applied at dosing rates of approximately 25% of the copper concentration used in conventional copper-based algaecides.

The City’s consultants recommend this product based on its:
• Established use in other waterbodies within Western Australia,
• Successful application in other waterbodies that have experienced cyanobacteria (blue-green algae) blooms, and
• Significantly lower copper concentration compared with traditional copper sulphate products, as it is a fully dissolved liquid formulation containing dispersants that assist mixing throughout the water column, thereby enabling lower dosing rates than crystalline products.

The contractor will be responsible for applying both the EarthTec algaecide and Phoslock treatment.

To ensure the Phoslock treatment is as effective as possible, EarthTec will be applied to Lake Brearley up to two weeks beforehand. Dosing is scheduled to commence on 26 February and should take one day to complete. It is expected the application will result in algal cell death within approximately two weeks of application. This expectation is based on published research, advice from potential suppliers and previous field experience.

Based on observations from applications in other waterbodies, a temporary decrease in dissolved oxygen (DO) has been noted following treatment. A reduction in DO can affect aquatic ecosystems, potentially leading to changes in biodiversity. Available findings from the use of EarthTec indicate such effects have not resulted in significant ecosystem collapse or notable generation of hydrogen sulphide (H₂S, sometimes associated with a ‘rotten egg’ odour).

A water monitoring program of the dosing itself and concentrations of key water quality parameters, such as pH, dissolved oxygen and nutrient concentrations will be undertaken throughout the period of application and in the following weeks post-application. The City has measures in place should any adverse impacts be identified.

Brickworks Biofilter

Establishing a treatment biofilter at the upper end of Brickworks Lake is proposed within the Masterplan. Modifying Brickworks Lake to a biofilter will assist in treating inflows from the upstream catchment to the north of the lakes before water enters the main lake system. Biofilters function by passing water through specially selected vegetation and engineered soils, which remove nutrients and other pollutants, improving overall water quality and reducing nutrient loads entering the lakes.

A draft design has been prepared and is undergoing an internal review to assess its cost, constructability and overall effectiveness. This work forms part of the broader landscape redesign process. It is anticipated tenders for this work component will be advertised in Q4 2026.

Water Recirculation Pumping System

Establishing a water recirculation pumping system for Lake Brearley forms part of Phase One. Such systems are commonly used in urban lake environments to increase water movement, reduce stagnation and improve overall water quality. The project is progressing through the design development phase. Finalisation of the power supply requirements is pending, and the timing of these works will be dependent on whether there needs to be power supply upgrades and approvals from Western Power.

Landscape Redesign

A detailed ground survey was undertaken to map shoreline levels, access points and surrounding infrastructure to inform safe site access, staging areas and environmental protection measures. This survey, along with the bathymetric survey, has informed and enabled the development of the broader landscape restoration design. The project then progressed to the development of landscape concepts for 15 areas surrounding the lakes to ensure these achieve the ecological objectives of the Masterplan.

This Landscape and Green Infrastructure Assessment and Design Response was presented during community engagement sessions on 4 and 6 December 2025. The purpose was to provide a clear understanding of the current conditions and communicate why ecological and landscape interventions are necessary. A community survey through Engage Bayswater provided an opportunity for residents to respond to each of the 15 areas. The survey closed on 5 January and consultants are using this feedback, in collaboration with City staff, to refine the landscape restoration plan.

Estimated implementation timeline

In conjunction with its consultants, the City has updated the estimated implementation timeline, available in the Documents section of this webpage or by clicking the link below.

Implementation timeline [PDF, 73KB]