Care needed in tackling algal bloom in Swan River

11/2/00

Water Resources Minister Kim Hames said the Swan River Trust was looking at a range of actions that may be used to combat a toxic algal bloom in the Swan River.
"We have to be very careful because the algae will release its toxins as it dies so if we take any action to kill off the bloom we must ensure we don't worsen the problem,"Dr Hames said.
"Options we are looking at include spraying salt water or stirring up the river to bring salty water from the bottom into the surface layer of freshwater which is where the bloom is lying and multiplying.
"Mechanically skimming the algae off the surface is another option but we would need to be careful how and where it is disposed.
"Modified clay treatment and oxygenation are two techniques being tested and there may be some potential to use these in the current situation."
Authorities have renewed the warning for people to avoid contact with the water in a wide section of the Swan River.
Monitoring over today has confirmed the toxic blue-green algae Mycosystis aeruginosa is still present in patches of the river stretching from Maylands to Point Resolution.
Health Minister John Day confirmed the Health Department's advice that people should avoid any contact activity with the river in the affected areas.
"Local governments have been advised and are working with the Health Department in erecting warning signs at key foreshore sites around the river," he said.
"Yachting and boating clubs, riverside businesses and relevant State agencies are all being kept informed.
"The Department of Transport and Swan River Trust boat crews will be on patrol on the weekend to warn people of the issue."
Dr Hames said the Swan River Trust would continue close monitoring of the situation by sampling the river, keeping a foreshore watch and using aerial imaging.
"We are getting advice from eastern Australia where toxic blue-green algal blooms are a common occurrence and from the Bureau of Meteorology on weather and tide conditions over next few days," he said.
"Modelling advice from the Centre for Water Research will give us information on river behaviour that will affect living conditions of the bloom."

The Health Department has set up a Health Call Centre line (1800 220 400) and the Swan River Trust has a dedicated information line (016 982 027) to provide information to the public.
Dr Hames said the bloom was a highly unusual event, brought about by the recent rains which resulted in large amounts of fresh water and nutrients running into the river while hot temperatures and calm days provided ideal conditions for the bloom.
Commercial fishing operatives on the Swan River were advised by Fisheries WA earlier in the week to cease fishing in the affected areas.
The department recommended that recreational anglers do not take fish or other species such as prawns, crabs or mussels from the affected areas.
Media contacts: Mark Thompson 9213 6600 Caroline Lacy 9424 7450