Maylands Lakes Water Quality & Amenity

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 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.

The City of Bayswater is working with the Friends of Maylands Lakes 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 successfully obtained grant funding to support the restoration.

A Community planting day will be held on June 25 and will begin the process of creating a biodiverse natural area. To get involved check the City's website https://www.bayswater.wa.gov.au/communityplantingdays

The eight-week dredging program has now been completed, and the contractor has demobilised from site. It is estimated that the contractor was able to dredge >90% of the target area. Given the operational uncertainties associated with the project, such as dredge access, anchor point locations and pumping distances, achieving that level of coverage is considered a good result. Based on the experience from dredging Lake Bungana, it could take approximately 18 months for the dredging in Lake Brearley to improve water quality and clarity.

Power has been reconnected to the mechanical mixer and the solar powered ultrasonics returned to optimal locations last week. Post-dredging sediment sampling will be undertaken to verify the effectiveness of the dredging program at removing the nutrient rich sediment. Fencing will be realigned this week to enable residents to access the path adjacent to Lake Brearley but keeping the sediment bags secure while they dry which is anticipated to take 4 - 6 weeks. Once the sediment is sufficiently dry the bags and limestone pad will be removed and the grass and reticulation reinstated. While the lake has been fenced off City officers have taken the opportunity to plant approximately 400 sedges along the limestone walls, adjacent to Tourer Court and at Hinkler Loop. This planting will contribute to improving biodiversity in the lake and nutrient removal. City officers will continue monitoring of the water quality and midge levels to assist in understanding the effectiveness of actions taken to date.

Following positive results on the amount of sediment being removed as well as the progress of dredging in Lake Brearley, the dredging contractor, Apex Envirocare has been instructed to complete the full 8 week dredging program. To date approximately 68% of the area targeted for dredging has been completed and the dredge will move to complete the north western section of the target area. The sediment is consolidating well in the two geopro bags so a second laydown pad will not be required. The dredging is due to be completed the week of 28th March 2022 and it is anticipated the sediment bags and laydown pad will be removed by early May 2022.

In accordance with the Maylands Lakes water quality improvement plan, dredging of Lake Brearley commenced this week. The dredging is targeting the removal of nutrient rich sediment that has built up in the lake. The dredging program is scheduled to run for eight weeks.