"With this warm weather hanging around, caution is advised for people and their pets until this warning has been removed from the Lawa website.
"We've seen sites that are safe to swim in, move to dangerous warning levels within a matter of days.
"The warm weather is accelerating that and it's important to check the latest status on Lawa."
Greater Wellington is monitoring popular swimming spots around the region weekly to ensure the community knows when and where it's safe to swim.
Members of the public who think they or their dogs have been in contact with toxic algae should see a doctor or ring Healthline on 0800 611 116 and take the dog immediately to the nearest vet.
Toxic algae
What causes it:
Toxic algae in our rivers are actually not algae at all, but cyanobacteria, which is commonly referred to as blue-green algae. Cyanobacteria are naturally present in all New Zealand waterways but can grow to dangerous levels when the weather is particularly hot and dry. During summer, we tend to see more harmful blooms in our region's rivers, making swimming especially dangerous for people and dogs. These blooms last until heavy rain flushes the river.
Staying safe
Toxic algae is considered a health risk to people, particularly young children. Because kids are inquisitive and more likely to pick it up and then put their fingers in their mouths, special care should be taken when swimming with them.
Swallowing water containing toxic algae can make humans very sick nausea, vomiting and diarrhoea. Contact can also cause irritation of the skin, eyes, nose and mouth.
Toxic algae is lethal to dogs. It contains a neuro-toxin that kills dogs by blocking their nerves from communicating with each other.
If an alert has been issued, or you think you have spotted a toxic algal bloom, keep your dog on a lead and away from the water to ensure they don't eat any algal mats.
In extreme cases, a dog may die within 30 minutes of eating toxic algae. Preventing poisoning is better than any known treatment.
Symptoms in dogs include seizures, severe vomiting and diarrhoea. If your dog has any of these sypmtoms, take them to the nearest vet immediately. Tell the vet you think it may have ingested toxic algae, so that they can give it the best treatment as quickly as possible.
Toxic algae blooms appear differently in lakes and rivers.
Rivers
Look for black, green or brown slime on rocks, or brown or black "mats"at the river's edge that have a velvety texture and earthy/musty smell.
If you see toxic algae, be cautious and avoid the site, particularly if you have a dog.
Check for alerts on the Lawa website, which provides live updates on where it is safe to swim.
Lakes
Lakes in the Wellington region are not monitored as rivers are much more popular. However, it is important to know what to look for in lakes.
If the water has a "pea soup appearance", it could contain toxic algae. Discoloured, cloudy water with small green blobs suspended in it should be avoided.
Ocean:
Toxic algae is quickly deactivated by saltwater, so is not harmful once it reaches the sea.
However, ensure the area is safe for swimming by visiting the Lawa website, as the sea can contain harmful bacteria.
What we're doing about it:
Unfortunately, because of the impact of hot dry weather on toxic algae blooms, there is no quick or obvious solution to prevent them. For this reason, people are strongly advised to learn what toxic algae looks like, and swim elsewhere if they see it.
Greater Wellington works with other councils and Regional Public Health to monitor the safety of waterways, and issue warnings when blooms occur. This includes signs at key sites where toxic algae is considered a hazard, and updates online.
- source Greater Wellington Regional Council
• Lawa website: www.lawa.org.nz/
