Maylands Lakes

The treatment undertaken by the City before the Christmas and New Year period has resulted in a reduction of midge numbers.

The City has continued its midge treatment program in 2024, with Lake Brearley treated on 9 January.

The City will monitor and treat on a 14-day rotation during the midge breeding season.

The City will continue to monitor midge numbers.

The City of Bayswater midge treatment program will continue over the festive season.

Lake Brearley is treated with a hybrid larvicide on a constant 14-day rotation during the midge breeding cycles. This treatment forms our ongoing mosquito control of the lake.

The lake is then treated with a higher concentration as per our Australian Pesticides and Veterinary Medicines Authority off label permit. This is applied by a commercial pellet spreader mounted onto an all-terrain amphibious vehicle.

The lake will be treated on or as close to 22 December 2023 with the higher dosage to give sufficient coverage over the 10-day Christmas break - with the heavier dosing generally providing a 14-day reprieve.

The City will also continue to monitor the traps during the holiday period.

The City is pleased to advise the Maylands Lakes - Interim Water Quality Report 2022/23 is now available

This report conducts a preliminary review of the data collected between March 2022 and September 2023 with reference to the existing dataset (2019 onwards), and provides updates to the City to inform future lake monitoring and management practices.

Key findings of the report include:

• Since installation of the mixing units in 2021, Lake Bungana has had improved visibility. The lake appears to be responding well (with regard to general water quality and clarity) to being mixed for a prolonged period, with relatively stable monitoring results. This suggests that no additional management intervention is required at this time. However, a potential trend of reduced water clarity (from March 2022 onwards) should be closely monitored

• Conversely, Lake Brearley continues to show poor water clarity, higher nutrient concentrations and more intense algal blooms than Lake Bungana. Additional intervention may therefore be required to consistently achieve a similar amenity as Lake Bungana.

• The effectiveness of current management of the Maylands Lakes may be limited by the lake size, shape and depth, algal populations, nutrient levels and/or initial conditions at the time of mixer deployment.

The City regularly monitors water quality at Maylands Lakes and has recently provided water sampling results to the WA Health Department for analysis.

The Department has assessed the results and noted there are high levels of cyanobacteria present in Lake Brearley and Lake Bungana which are not suitable for activities where there is direct contact with the water or the risk of ingestion.

As the water in these lakes is not used for recreational or drinking purposes, there are no specific guidelines applicable; however, the cyanobacteria levels will need to be taken into consideration if the water is used for alternate purposes.

The City is working to improve water quality in these lakes as a priority. Signage exists around the perimeter of the lakes advising the community to avoid contact with the water. The fountain in Lake Brearley, which is connected to an automatic shut-off during windy conditions, has also been completely shut off.

On Tuesday 12 December 2023, Council voted to engage a specialist consultant who will assist the City in establishing a Scientific Advisory Panel to develop and oversee a masterplan to address the environmental conditions leading to the over-abundance of midge, cyanobacterial blooms and other water quality issues at Maylands Lakes.

The City acknowledges the negative impact the poor water quality, algal blooms and midge are having on residents near Maylands Lakes.

The City will investigate a water mixing trial that aims to improve the water quality of Lake Brearley while managing any associated risks.

Council has approved the allocation of funds in its 2023/24 Budget.

The City of Bayswater is working with the community to restore and enhance the vegetated area around Lake Bungana as part of water quality improvement works.

The project aims to:

• Improve water quality
• Provide habitat for native animals
• Improve the visual amenity of the Lake.

The area in question is classified as completely degraded and dominated by Melaleuca quinquenervia and Casuarina cunninghamiana. These species have been identified as requiring management by the Department of Biodiversity Conservations and attractions (DBCA). As part of the Maylands Lakes Restoration Plan the City is seeking to increase riparian vegetation along the lake shore to assist with nutrient stripping and create a more diverse habitat reflective of a naturally occurring environment to provide habitat for fauna. The invasive species have formed a root shelf preventing the establishment of riparian vegetation and turtle nesting at the site. Works are being undertaken in collaboration with the friends of Maylands Lakes who support the restoration.

UPDATE of RESTORATION WORK

The planting day has been finalised and it will be held on the 4th of August 2024. Treatment of the woody weeds has begun, and removal will take place in early July to make way for the new plants.

The below map highlights an additional area that has been added to the existing revegetation schedule. It consists of non-endemic Casuarina species and as in other locations, it is causing foreshore degradation. It is also preventing the germination and growth of other species.

A notification will be posted when major works are scheduled to commence, however smaller trees will start to be removed along with others around the Lakes prior to that time.

The City of Bayswater has prepared a revegetation plan to restore the bushland around Maylands Lakes over the next ten years. Non-endemic species have grown to become detrimental to the natural balance of the ecosystem within the region. Many years ago, during development of the Lakes, these were planted without the knowledge of their effects on the environment that we understand today. In order to rectify this, ongoing clearing of smaller introduced trees will occur around the entire area. Clearing of large stands of trees will take place as a staged process, as seen on the map, allowing the new vegetation to establish, providing habitat for the various species of fauna around the lakes and attract those that have not been present for many years due to the loss of natural habitat.

Rehabilitation works will begin at Lake Brearley in accordance with the Maylands Lakes Conservation Plan. This will restore and improve the vegetated area around the Lake as part of the water quality improvement works. The project aims to:

• Improve water quality.
• Provide habitat for native animals.
• Improve the visual amenity of the Lake.

Works will occur from May to June 2023 and will involve:

• Removing the non-endemic species Casuarina cunninghami, Melaleuca quinquenervia and Callistemon which are dominating the area and preventing the development of a fully functioning foreshore habitat.
• Modification of the bank to allow revegetation.
• Community planting day to install native endemic plant species.

During works a temporary fence will be in place to ensure community safety with pedestrian management.

Should you have any queries regarding the above, please contact the Manager Sustainability, Environment and Waste, Alex Devine, on 9272 0660

The City of Bayswater will be undertaking works to remove vegetation on the islands in Lake Brearley (indicated in red, on the attached map). Clearing will only occur where evidence of nesting has occurred the other islands will be monitored for activity. Contractors have been arranged to carry out the removal of the following species which have been identified as invasive by the Department of Biodiversity Conservation and Attractions (DBCA):

• Casuarina cunninghamiana

• Schinus terebinthifolia

The islands are populated in the winter months by cormorants, which are contributing to water quality challenges within Lake Brearley. The birds are not utilising the site at present, thus allowing works to be undertaken. Following the removal of invasive vegetation, the islands will be revegetated with endemic species to promote biodiversity. This action is part of the City of Bayswater’s continuing efforts to mitigate water quality issues within the Lakes. The change in vegetation will result in the cormorant population moving to more appropriate areas away from the lake, and will ease the nutrient loading that they had previously added to the lake. Bird droppings will be removed from the islands before any vegetation is planted, which will also assist in reducing additional nutrients entering the lake. The works will be undertaken in February and should last approximately a week. Works will include the use of chainsaws and machinery, and will be undertaken during business hours.

The City engaged GHD to provide a technical assessment of the dredging undertaken at Lake Brearley. GHD have provided their report to the City, and concluded the overall objectives of the program appear to have been substantially achieved, as follows:

• Completion of dredging in the identified priority area;

• More than half the available nutrients in the target area have been removed (an estimated 59% of total organic compounds, totalling approximately 17 tonnes); and

• Dredging was significantly more successful than the Lake Bungana dredging works, recovering approximately 187m3 vs 56m3 of dewatered silt.

It is anticipated the removal of nutrients via dredging will work in concert with the other long-term water quality initiatives (mechanical mixers and solar powered ultrasonic units) to progressively reduce eutrophication, algal blooms and midge populations over time. A copy of the full GHD report is available in the documents section.

The limestone from the dredging laydown pad is being reused to create paths in natural areas in the City. The first path has been completed at Maylands Samphire's recently and the remaining limestone will be removed in coming weeks to create a path in Lightning Swamp Bushland.