Forest Lake has been struck by an infestation of blue-green algae, with residents complaining of a nasty stench and voicing concerns over toxic water conditions.
The Forest Lake Dragon Boat race, which is the highlight of the Dragon Boat Festival event, was called off due to rising levels of algae in the lake in June 2024. Since then, algae levels have continued to increase, creating a nasty smell and gradually turning the water green.
Local resident Shane Brahim said the lake’s current condition appears to be contributing to the frequent deaths of wildlife at the lake.
“People wonder why birds are dying … our lake is disgusting,” he said.
Forest Lake resident Chrystal Battesse said she came to sit by the lake in October and was very disappointed by its worsening condition.
“The smell isn’t nice either,” she said.
Photos by Chrystal Battesse (left) and Shane Brahim (right).
Blue-green algae is a toxic form of bacteria that thrives on the surface of still water when it has access to plenty of sunlight and nutrients.
Contact with blue-green algae or contaminated water can cause harmful reactions in humans and animals, including skin and eye irritations, vomiting, nausea, muscle weakness and cramps.
High concentrations of blue-green algae can also kill fish and other native wildlife, or may cause them to become very sick.
The lake experienced a similar problem in 2019, when algae levels turned the lake swamp-green and residents complained of the smell up to 150 meters away.
A Brisbane City Council (BCC) media spokesperson said the council was currently managing a multi-pronged response to rectify the algae issue at Forest Lake, which involves scientific analysis and technical advice.
“Council has engaged multiple branches, including Public Space Operations, City Projects Office and Natural Environment, Water and Sustainability Branch, in forming a collaborative response to this situation.
“The particular bacteria that has been detected at Forest Lake requires careful consideration in our approach, with respect to ecological life and connected waterways downstream.
“Recent above-average rainfall and warm weather have created ideal conditions for the blue green algae to flourish, and have consequently hampered Council’s response.
“High levels of nitrogen and phosphorus amplify the growth of the algae bloom. These algae bloom events are also exacerbated by stormwater run-off in suburban areas that contain domestic garden fertilisers.”
Water scientists from the City Projects Office have been in contact with several organisations regarding blue-green algae treatment methodologies and product trials
Existing water quality data will continue to be analysed, with another round of extensive scientific testing taking place in mid-December.
Brisbane City Council said further discussions and proposals are also taking place regarding the installation of hardware to maintain the lake and improve the overall health of the water.
“The intention is to prevent stagnation of the water by aerating it to allow more efficient circulation, which will improve dissolved oxygen levels and provide more consistent water temperatures.”
Council is also engaging with the State Government regarding trials, treatment options and methodologies for the lake based on state guidelines and policies.
