The amber alert for Clarrie Hall Dam has been downgraded to green and a green alert has now been issued for Bray Park Weir.
A green alert means that blue-green algae is present but in low densites. At these levels, the blue-green algae typically do not pose a threat to recreational activities, stock or domestic use.
The original amber alert for Clarrie Hall Dam was issued on Friday, 25 September, 2020 but didn’t affect Tweeds water supply as it was ‘being drawn entirely from the Tweed River without any releases from Clarrie Hall Dam, isolating the amber alert to the dam water,’ according to the Tweed Shire Council.
Blue-green algae occur naturally and can reproduce quickly in still or slow-flowing water when it is warm and sunny and there are sufficient levels of nutrients in the water body.
Testing during the amber alert issued for Clarrie Hall Dam on Friday 25 September 2020 showed that the algae species did have the gene capable of producing toxin, but there was no evidence that any toxin had been produced.
‘Even if this species were found, our water treatment processes remove blue-green algae from the water when blooms occur so our water would still be perfectly safe to drink,’ said manager Water and Wastewater Operations Brie Jowett
‘Knowing that the gene capable of producing toxin had been present, together with the continuing favourable conditions for blooms, Council is taking a precautionary approach and continuing to restrict recreational activities at the dam,’ Ms Jowett said.
‘Warning signs at the dam wall and Crams Farm will stay in place until we are confident there is no risk to recreational kayakers or fishers coming into contact with the water.’
Council will continue to test the water at the dam, in the river and at Bray Park Weir pool.
Water affected by blue-green algae appears to have a green paint-like scum on the water, near the edges, or greenish clumps throughout the water.
Anyone who thinks they may have been in contact with blue-green algal water is advised to seek medical advice if symptoms appear.
For the latest, visit Council’s website www.tweed.nsw.gov.au/WaterAndWastewater