Warm weather increases risk of blue-green algae

With the weather warming up, Townsville residents are being reminded of the potential for a blue-green algae outbreak in the Ross River Dam this summer and its possible impact on water supply.

Mayor Jenny Hill said blue-green algae was a common occurrence in waterways across Australia, with blooms exacerbated by excess nutrients being washed into dams and water courses. Warmer weather and increased sunlight help the algae flourish.

However, Cr Hill said Townsville City Council had implemented a number of initiatives to minimise the risk of algal blooms in the dam.

“Council is committed to delivering clean and healthy water to the Townsville community,” Cr Hill said.

“Our water supply is rigorously tested to ensure it meets all health standards and is safe to drink, with test results provided to the Department of Health and the Office of the Water Supply Regulator.

“Council acknowledges and regrets the impact of blue-green algae on our water supply earlier this year which led to a temporary discolouration of the water supply.

“Council officers have been working alongside industry experts on the management of blue-green algae and have developed a management plan, with actions to be implemented as algal bloom levels rise.

“This is designed to minimise the impact on the community from blue-green algae.”

Initiatives implemented to address possible blue-green algae blooms in the dam and their impact on the water supply include:

• installing aerators in Ross River Dam to improve dissolved oxygen concentrations
• starting construction of two new clarifiers at the Douglas Water Treatment Plant (DWTP) at a cost of $27.5 million, with construction forecast to be completed by September 2022
• installing powdered activated carbon (PAC) dosing at the treatment plant to mitigate taste and odour and toxin risk
• adding pre-chlorination to all modules at DWTP to improve soluble metal removal
• additional monitoring through both Townsville Laboratory Services and the installation of new onsite analysers at Ross River Dam and DWTP.

“We have experienced a relatively warm winter and as we approach summer and the temperature increases, there is a potential for algal blooms to again develop in the dam,” Townsville Water and Waste Committee chairperson Russ Cook said.

“Council will continue to monitor blue-green algae and relevant water quality parameters in the Ross River Dam and adjust treatment processes.

“However, in the event of an algae outbreak, the community may again see some temporary discolouration of water.

“Should the algal bloom count reach very high levels, there will be impacts to the amount of water able to be treated at the water treatment plant, which may result in restrictions on water availability.

“We will continue to look at every option available, both engineering and environmental, to minimise any possible impact.”