The weir on the Richmond River at Casino, where the latest outbreak of blue-green algae has occurred.
The weir on the Richmond River at Casino, where the latest outbreak of blue-green algae has occurred.

Bloom could be a blight on Casino

WHILE Casino grapples with a blue-green algal bloom in the Richmond River, the rest of theregion is free of the toxic growth.

The most recent test on Lennox Head’s Lake Ainsworth, for instance, returned an all-clear.

But with limited baseline numbers of the ancient algae present, there is always the chance an outbreak could reoccur in the coastal lake.

Blue-green algae indicates a watercourse stressed by a nutrient imbalance, but does notalways appear when conditions are right.

NSW Water algal monitor Brian Dodd, who is based at Grafton, said the last time the Richmond River had an outbreak was in November 2002, when the region was paralysed by drought and Rocky Creek Dam dropped to 23 per cent.

Since that time conditions have been right for blooms, but none has occurred.

The possible triggers for the Casino outbreak include high loads of nitrogen and phosphate washed into the river during recent high rainfall, followed by last week’s high temperatures.

While the outbreak is situated at the intake for the town’s drinking water, the toxic algae can be filtered out making the river water suitable for drinking.

According to Mr Dodd, the algae – which lived on Earth before the creation of oxygen – behaves in weird and wonderful ways.

“People ask me how long will the algae hang around, and I say ‘how long is a piece of string?’” he said. “Often it appears one day, and then a week later it is gone. It is just one of those things.”

Another form of blue-green algae is the marine organism trichodesmium, which appeared in the Evans River earlier this month.

It too causes eye and ear irritation and is often mistaken for a paint spill because of its colour, and when it dries it can look like toilet paper.

Ballina Shire Council environmental services manager Graham Plumb said when that happened people tended to ring up the council to complain its sewage works were malfunctioning.



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