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Recreational Water

The water quality at more than 80 popular coastal, river and lake recreation sites and shellfish beds in the region are surveyed and monitored by Bay of Plenty Regional Council and Waikato Regional Council from October to March each year.

The waters are tested for bacteria and toxin forming algae species.  This includes benthic cyanobacteria (Phormidium) in rivers and streams.  If a recreational water site is found to be significantly contaminated, with risk to public health, Toi Te Ora Public Health informs the public by issuing a health warning and the local council erects warning signs.

If you swim in or drink contaminated water, you risk getting sick.

Water can be contaminated with toxic algae (blue-green algae/cyanobacteria) or animal faeces from rural or urban run-off.

As a public health precaution, it is routinely recommended that people avoid swimming in rivers, streams and harbour areas for 48 hours after heavy rainfall events.

What to look for

  • If you notice the water in your local lake, river or beach is murky or has a musty smell, go somewhere else.

  • If you notice the river bed or rocks covered in algae and looks like black/brown leathery mats, go somewhere else.

  • Avoid swimming for up to 48 hours (two days) or until the water looks clear after heavy or prolonged rain.

Health risks

Toxic Algae

Toxic algae, also known as blue-green algae and cyanobacteria, are capable of producing toxins that are harmful to humans and animals, whether swallowed or exposed to skin during swimming, kayaking or water-skiing.

Symptoms include fever, headaches, dizziness, skin rashes, stomach cramps and aggravated hay fever and asthma and damage to the nervous system.

Download our fact sheet on Toxic Algae (blue-green algae / cyanobacteria)

Sewer Overflows

In built up areas such as Tauranga Harbour there is a possibility of sewage discharge from the reticulated sewage system.  This can lead to contaminated water.  Should this occur, the local authority would advise the public that an unplanned sewer overflow has occurred and remedy the affected area.

For more information about sewer overflows, contact your local council.

Other contaminants

Water contaminated with animal and human faeces can lead to gastrointestinal illnesses (tummy bugs) such as Salmonella, Giardia, Campylobacter and Cryptosporidium.

People can also experience cold and flu-like symptoms and skin, eye and ear infections.

Swimming, spa and geothermal pools

Contact us if you have a complaint or enquiry regarding the hygiene of a local swimming, spa or geothermal pool, or if you suspect you obtained an infection/illness from using a public pool.

Resource: Keep you head above water - Amoebic meningitis

 Swimmers Itch

Swimmers itch, also known as ‘duck itch’ or cercarial dermatitis, is caused by exposure to tiny larvae or cercariae in shallow, warm water and can cause an allergic irritation of the skin.

Symptoms can include an itchy or tingling sensation that develops in to tiny red spots, pimple-like bumps (papules) and occasionally, hives or blisters.

You can reduce the risk of being affected by avoiding shallow areas of water, particularly where there is vegetation and/or evidence of bird life, and washing or showering  with clean water following any contact.  Drying yourself off with a towel after swimming can also help.

For more information on swimmers itch, see DermNet NZ.


Seabathers’ Eruption

People who get itchy, sore rashes under their swimming costume after swimming at a beach are likely to have been stung by tiny, transparent jellyfish or anemone larvae. The rash is called “seabather’s eruption” and it is the skin’s reaction to the toxin injected by the larvae of jellyfish or anemones.  

This rash is often called “sea lice bites”, but sea lice are actually a parasite of fish and they can produce a rash on uncovered skin.  

Symptoms of seabather’s eruption include pain, burning and itching. The rash appears as red swollen marks on areas of skin that were covered by swimwear.   People can get skin tingling before leaving the sea, and the rash tends to occur after getting out of the water.  The rash may not appear until several hours after being in the sea. The rash and itchy can vary from mild to severe lasting up to a week or more. Children and those with a severe reaction can become unwell with headaches, nausea and lethargy for several days.

Figure 1: Seabathers' Eruption rash.  Source: DermNet NZ

Warm weather and onshore winds bring tiny jellyfish and anemone larvae close to the shoreline and being so small, they can get trapped unnoticed in swimwear, or in peoples’ hair while swimming. As a swimmer gets out of the sea, water drains from the swimwear and traps the jellyfish between the fabric and the skin, causing the stinging cells to release their toxin.  The toxin can also be released by washing in fresh water and rubbing affected skin with a towel.  

You can treat the rash by washing the affected area with salt water.   Fresh water can be used, but sometimes can make the rash worse. Hydrocortisone cream (1%) applied 2-3 times a day over 1-2 weeks is the most useful treatment.  Calamine lotion, antihistamines, and anti-inflammatory medicines such as ibuprofen can also help reduce symptoms.  Ask your pharmacist for advice.

If you are concerned or if symptoms are severe see a doctor or call Healthline for advice on 0800 611 116. Healthline operates 24 hours a day, seven days a week.  

For more information see DermNet NZ.

Sea Slugs

Grey Gilled Sea Slug (Pleurobranchaea maculata)Sea slugs are a wide-ranging organism in the marine environment of New Zealand.  Sea slugs may be found washed up on beaches anytime, anywhere, probably related to their breeding cycle and prevailing weather patterns.  The slugs are mottled grey or sand-coloured, usually 2 to 2.5cm in length. They can grow up to 10cm.

Toi Te Ora - Public Health Service advises that:

  • Children and pets should be supervised on beaches.

  • Adults, children and pets should not eat anything found washed up on any beach.

  • Parents need to be aware of where their children are swimming or playing and what they are handling.

  • Sea slugs on any beach must be avoided.

  • TTX is extremely toxic to humans and even a very small dose could be fatal.

Early symptoms of TTX poisoning include numbness and tingling around the mouth and nausea. This numbness and tingling can then spread to the face, tongue and other areas, with paralysis, co-ordination problems and slurred speech. Medical attention should be sought immediately should any person become unwell after contact with a sea slug.

Information for First Aid Response for Tetrodotoxin (TTX) Poisoning is available on the Auckland Regional Public Health Service website.

For more information about Sea Slugs, visit the NIWA website.

Further information


Contact us for more information.  View current health warnings here.


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