Rain reduces water demand and provides temporary reduction in blue-green algae levels in dam

Date published: 10 December 2021

North Queensland’s tropical weather continues to influence algal blooms in the city’s water supply, with recent rain and overcast conditions reducing blue-green algae counts in the Ross River Dam.

The level of blue-green algae in the dam has reduced from around 200,000 cells/mL at the beginning of November to around 39,000 cells/mL currently.

However, with unreliable rainfall forecast in the coming weeks, Mayor Jenny Hill has reminded the community that blue-green algae continues to have an effect upon Townsville’s water supply.

“Recent rain and overcast conditions have provided a temporary reprieve from higher blue-green algae levels. Weather conditions have both reduced water use generally and slowed algal bloom growth in the dam,” Cr Hill said.

“A return to warm, clear days is expected to see the blue-green algae level increasing again.”

Cr Hill said Council officers continued to work alongside industry experts on the management of blue-green algae in the dam and treatment process.

“The reality is that blue-green algae is a common occurrence in waterways across Australia, with blooms exacerbated by excess nutrients from the catchments including adjacent properties, being washed into dams and water courses. Warmer weather and increased sunlight help the algae flourish,” she said.

Should the algal bloom count reach very high levels, there may be reductions in the amount of water able to be treated at the water treatment plant, which may result in a need for water conservation measures.

A significant blue-green algae outbreak in Ross River Dam could lead to some temporary restrictions on potable water production and possibly some discolouration of water, but the community also play a role in helping reduce that impact by being conscious of how much water they use in their homes.

“Water usage rates are key because when we have a significant blue-green algae outbreak, it can impact the filtration and volume of treated water available for public use.”

Council continues to monitor blue-green algae and relevant water quality parameters in the Ross River Dam and adjust treatment processes as required.

“We will use every option available, both environmental and engineering, to minimise any possible impact of significant blue-green algae outbreaks” Cr Hill said.

For more information, visit Townsville Water Updates.