Waikanae River issued red alert warning for toxic algae

Toxic algae warnings are in place at the Waikanae River.

Toxic algae, more commonly known as blue-green algae, has been found in the Waikanae River, and red alert level warnings are now in place.

The warnings are for the river at the old State Highway 1 and Jim Cooke Memorial Park.

The toxic algae, which is not algae at all but rather cyanobacteria, is harmful to humans and lethal for dogs if ingested.

Greater Wellington senior adviser of integration and insights Penny Fairbrother said detached algal mats were widespread at both sites, with the potential to harm pets who love playing in the water.

“The warm autumn air and lack of rain have allowed toxic algae to regrow, forming mats at the river’s edge that can be very tempting to dogs.

Toxic algae mat growing on a riverbed.

“Toxic algae are a neurotoxin that acts a bit like snake venom. Even the smallest amount — the size of a 50¢ coin — is enough to kill a dog.”

Fairbrother said toxic algae could be identified by looking out for leathery, dark green or black mats clinging to rocks, or clumps of brown at the river’s edge.

“The best antidote for toxic algae is to avoid it altogether.”

She said dog owners who thought their animals had swallowed toxic algae, or were showing signs of lethargy, muscle tremors, fast breathing, paralysis or convulsions, should go to the nearest vet immediately.

“People who have been in contact with toxic algae and are feeling unwell should see a doctor or ring Healthline on 0800 611 116.”

Greater Wellington encourages everyone to check the Land, Air, Water Aotearoa (Lawa) website warnings and alerts before visiting rivers in the Wellington region.