The Toxic Algal Bloom Threat Growing In Australian Waters

A major marine algal bloom affecting parts of South Australia has put water quality back in the spotlight, with scientists warning that environmental conditions may be creating the perfect environment for more frequent outbreaks.

While harmful algal blooms are not a new phenomenon, experts say warmer temperatures, nutrient runoff, & changing weather conditions are increasing the risk of outbreaks across Australia.

The Murray-Darling Basin Authority has also reported elevated blue-green algae risks in several regions during 2026.

What Are Harmful Algal Blooms?

Despite their name, blue-green algae are not actually algae. They are a type of bacteria known as cyanobacteria that naturally occur in Australian waterways.

Under the right conditions, these organisms can multiply rapidly, forming what is known as a harmful algal bloom. Some harmful algal blooms can produce toxins that pose risks to people, pets, wildlife, & aquatic ecosystems. They can also lead to waterway closures, impact drinking-water treatment processes, & affect the taste & odour of water supplied to homes & communities.

South Australia's Bloom Draws National Attention

Much of the recent attention has focused on South Australia's ongoing marine algal bloom, which has affected coastal communities, marine habitats, tourism operators, & commercial fishing industries.

ABC News & The Guardian has reported that a second wave "could be imminent" highlighting ongoing concern among scientists monitoring the event.

The Growing Connection Between Climate Conditions & Water Quality

Experts say harmful algal blooms often occur when several environmental factors align.

Warmer temperatures can accelerate algae growth, while lower river flows & extended dry periods can create conditions where blooms are more likely to thrive.

At the same time, nutrient runoff entering rivers, reservoirs, lakes, & coastal waters can provide the fuel needed for rapid growth.

The South Australian event has highlighted the growing connection between climate conditions, nutrient runoff, & water-quality problems, with scientists continuing to examine how these factors may influence future bloom events across Australia.