The Department of Health has warned of a potentially toxic algal bloom that has formed in parts of the Vasse-Wonnerup Estuary on the outskirts of Busselton.
A bloom of the naturally occurring Lyngbya majuscula algae stretches upstream from Floodgate Road to James Richardson Park on Estuary View Drive. Downstream areas through to the ocean mouth at Forrest Beach are also likely to be impacted.
Executive Director Environmental Health, Dr Michael Lindsay, said the macro bloom had formed free-floating masses entwined with long hair-like strands, giving the water a clumpy green-brown appearance.
Dr Lindsay said the blue-green algae could cause severe irritation to eyes, skin, respiratory system or gastrointestinal system; and that people should avoid contact with the bloom.
"Recreational activities such as swimming, kayaking, water-skiing, jet-skiing, and fishing, crabbing and shellfish collection in these waters should be avoided, particularly where algal mats, scum or discolouration is visible," he said.
"Pets and livestock should also be kept away from the water while the bloom persists."
The City of Busselton has put up warning signs at the main access points to the affected waterways.
Dr Lindsay said farmed shellfish purchased in supermarkets and other commercial outlets in WA would not be affected, given the strict quality-assurance programs in place.
Anyone who comes into contact with the algae should immediately rinse it off with clean water and seek medical attention if they feel unwell.
The Department of Water and Environmental Regulation is monitoring the bloom and has opened its surge barriers (a type of floodgate) in the area to minimise upstream algal densities and the potential for fish deaths to occur.
Anyone who sees or suspects an algal bloom in a waterway should phone ALGALWATCH on 6250 8064 or notify the relevant local government. Fish deaths can be reported to FishWatch on 1800 815 507
