WATERNSW has issued a red alert advisory for high levels of potentially toxic blue-green algae in the Darling River at Tapio.

Blue-green algae is naturally occurring, and can reproduce quickly in still or slow-flowing water when there is abundant sunlight and sufficient nutrients.

Residents have been warned to avoid consuming untreated water from the waterbody and prevent pets and livestock from drinking this water.

People are also being advised to avoid recreational activities such as swimming, water skiing, canoeing and any other activity that brings them into contact with this waterbody until the red alert warning is lifted.

Blue-green algae may cause gastroenteritis, liver damage and other health issues if consumed, while contact can cause skin and eye irritations.

Fishers are also being warned not to eat mussels or crayfish from red alert warning areas and any fish caught should be cleaned and washed thoroughly in uncontaminated water, although avoiding fishing during a bloom is the best way to minimise risk.

Updates and information about blue-green algae blooms and red level warning areas can be obtained by visiting www.waternsw.com.au/algae or calling 1800 999 457.