Blue-green algae
Blue-green algae, also known scientifically as Cyanobacteria, are a group of photosynthetic bacteria. These accumulations are frequently referred to as 'blooms'.
Blooms are most often blue-green in colour but can also be:
- blue
- green
- reddish-purple
- brown.
Blue-green algae blooms are likely to occur more often when the water is warm and enriched with nutrients like phosphorus or nitrogen. Under certain conditions, blue-green algae can accumulate in thick layers at the surface or water's edge.
Impact on humans
It's possible for blue-green algae to cause illness in humans. The symptoms in humans include:
- rashes
- headaches
- fevers
- gastroenteritis
- seizures
- respiratory failure.
People may be exposed to these toxins:
- through contact with the skin (for example, when swimming)
- through inhalation of water containing toxins (for example, when close to irrigation sprays, motor boating or water skiing)
- by swallowing contaminated water, or
- by eating fruit, vegetables or leaves with blue-green algae surface contamination.
Impact on animals
Blue-green algae can also cause illness in animals, which most often come into contact with contaminated water from affected farm dams.
Download the fact sheet Blue-green algae: options for livestock drinking water (WORD - 115.0 KB) for more information.
Impact on your water supply
There are several steps that livestock producers can take to prepare for blue-green algae impacting and potentially cutting off a water supply.
Livestock farmers should consider:
- developing a plan for managing the situation where water availability becomes limited
- completing a stocktake of the quantity and quality of water currently available on-farm that will be toxin-free
- calculating the water requirements for animals that may need to be provided water if current sources become toxic, and therefore how many days' supply is available
- planning for additional on-farm storage should you need to quickly access alternative water supply
- planning for how sufficient water will be provided to livestock in the medium-term, which may include additional reticulation systems, finding agistment or selling stock.
See Managing blue-green algae in farm water supplies for more information.
More information
We have calculators and fact sheets to assist producers calculate water availability and animal demand:
- Blue-green algae problems in dams
- Irrigating with blue-green algae affected water
- Farm water solutions
Other resources:
Or see these pages from the New South Wales Department of Primary Industries:
- Blue-green algae
- Irrigating with blue-green algae affected water
- Water requirements for sheep and cattle