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Is it safe to swim?

Is it safe to swim?

Summer is a great time to enjoy our coast and waterways, but there are some times and places where caution is needed. 

Go to Land, Air, Water Aotearoa (LAWA) to check the suitability for swimming today, and to get the latest alerts.

Toxic Algae

The best thing you can do to keep safe is to know what toxic algae looks like and avoid it.

When the weather is hot and dry our rivers can produce toxic algal blooms. We monitor for toxic algae in rivers in the region, and work with councils across the region to keep river and stream users informed. 

The algae grows on submerged riverstones in a shiny brown/dark green to violet coating. The algae can also become unstable and detach from the riverstones and float to the surface forming small brown/black mats at the water’s edge. It is important to keep an eye on babies and toddlers who are inclined to put objects in their mouths. Seek emergency medical attention immediately if anyone in your group swallows toxic algae.

If you have been swimming in a river or lake and you have any of the following symptoms: nausea, vomiting, numbness, tingling, muscle twitches, shaking, weakness, breathing difficulties and potentially convulsions and loss of consciousness see your doctor immediately.


Dogs are at greatest risk from toxic algae because they love the smell of it and will eat it if they can. During a bloom, they must be kept on a leash along the river bank. If you suspect your dog has eaten even a small amount of toxic algae (coin sized) take it straight to the vet.

Greater Wellington is monitoring key swimming spots throughout the summer. We will issue an alert if toxic algae reaches unsafe levels, and extend monitoring to other sites, but please learn to recognise and avoid it.

Toxic algae FAQs

Tummy bugs

Stormwater entering our rivers brings with it a small amount of waste from animals (such as birds and dogs) and sometimes untreated human sewage from overflows. This can be a significant health risk after heavy rain. Only swim when the water is clear – this applies to rivers or the sea – and wait for 48 hours after heavy rain. Another good guide is “can I see my feet when I’m standing up to my knees in the water?”

If you notice a problem with water quality you can report it on 0800 496 734.

Learn more