Toxic algae was a recurring issue for the region’s fresh waterways when water temperatures warm and water levels lower. Algal mats usually grow on the rocks in the river-bed and from dark green or black mats, which will be leather-like and can break off and accumulate at river edges. As the algal mats dry out they become light brown color and have a particularly weird deep earthy or mouldy smell. The Greater Wellington senior environmental scientist Dr Mark Heath said toxic algae had increased to dangerous red alert levels in the Waipoua River over the last week, with those detached mats washing up at the river’s edge.
Toxic Algae red alert
The public has been given red alerts already. The Council advised the public not to swim and to keep dogs on leashes at the Waipoua River, Te Awa Kairangi / Hutt River from Birchville to Manor Park, and Pakuratahi River at Kaitoke campground. Dogs were mostly at risk because they liked the smell and taste of toxic algae. Even a small amount, about the size of a 50 cent piece – can be enough to kill a dog.
“We strongly advise against swimming and letting your dog off the leash. It is very likely as the weather gets warmer that this risk will increase. We all must scrub up on the facts so we can all keep safe this summer, as toxic algae can be harmful to people and dogs. Owners especially needed to be vigilant of their dogs sniffing out toxic algal mats which can wash up at river edges.” Dr Heath said.
Toxic algae was not the only harmful thing taking over in the water this summer, also bacteria from leaking pipes or run-off after heavy rain are found to contaminate swimming areas.”In general, a good rule of thumb is to stay out of fresh or seawater for 48 hours after rain, and always check for warning signs,” Heath said.
Greater Wellington is monitoring popular swimming spots on a fortnightly basis to make sure the community knows when it’s safe to swim. It has been advised that if anyone has been in contact with toxic algae and is feeling unwell see their doctor or ring Health-line and also to seek urgent medical attention for anyone with breathing difficulties or convulsions. If anyone thinks their dog might have swallowed toxic algae, they are advised to take it to the nearest vet immediately.