Protecting the quality of local recreational water

Community and Public Health is involved with the quality of coastal waters and freshwater waterways which are used for a range of recreational activities such as swimming, sailing, boating, surfing, water skiing, underwater diving and shellfish gathering.

The quality of recreational water is an important environmental health and resource management issue.

Health Risks Associated with Contaminated Water

Underwater view of water in New Zealand river looking up from the river bed. Source: LAWA.Water can be contaminated by human or animal excreta (poo) containing disease causing micro-organisms such as viruses, bacteria and protozoa.

Contamination poses a health hazard when the water is used for recreational activities such as swimming and other high contact water sports.

There is a risk that water will be swallowed, inhaled or come into contact with ears, nasal passages, mucous membranes or cuts in the skin, allowing pathogens or algal toxins to enter the body.

High levels of contamination can often occur after heavy rainfall. So people should avoid all rivers and beaches for at least two days after heavy rain.

The symptoms of exposure to contaminated water are usually minor and short lived. However there is the potential for more serious diseases including hepatitis A, giardiasis and cryptosporidiosis.

The best spots for water recreation this summer

Can I swim here? Check the water quality at Source: Environment Canterbury.Environment Canterbury’s contact recreation report is now available. Take a look and find out where will be good for swimming this summer.

The report grades 100 of Canterbury’s most popular swimming spots to show their suitability for swimming and recreation. Grades are determined by five years’ worth of water monitoring and sanitary survey data collected at each site.

Environment Canterbury provides this information to local health authorities and district councils so they can take the appropriate public health measures at each location. This includes signage and alerting community groups who commonly use the site.

Make sure you check out the Can I Swim Here? information on LAWA if you are thinking of getting into the water over summer.

“No changes in long-term grades have occurred at Lyttelton Harbour/Whakaraupō this year. This means the only spots deemed suitable for swimming are Paradise Beach – which holds a good grade – and Church and Cass Bays which both remain fair” said Shirley Hayward, surface water science team leader.

Swimming is not recommended at five sites across the South Canterbury region:

  • Near the stormwater outlet “Whale Creek” at West Caroline Bay;
  • Pareora River at Evan’s Crossing;
  • Pareora River at Pareora Huts;
  • Ewarts Corner boat ramp at Lake Opuha; and
  • Waihao River at Black Hole.

Monitoring for the 2023-2024 summer season begins in late November.

Swimming at any recreational site is not recommended within 48 hours after rainfall – regardless of the site’s grade. Rain can wash contaminants from roofs, land, drains and streams into waterways, making them temporarily unsafe for swimming.

Health Risks associated with Algal Blooms

Algal blooms are appearing more frequently in our waterways. Algal blooms in lakes can be blue/green in colour floating on the surface or colourless globules suspended in the water.

Algal blooms are also found in rivers as blackish benthic mat-forming cyanobacteria clinging to rocks or collecting at the riverbank. Some cyanobacteria species produce toxins.

Symptoms of exposure to toxic algae can range from allergic reactions, asthma, eye irritations, and rashes to rapid onset of nausea and diarrhoea to gastroenteritis to other specific effects such as liver damage and possibly developing cancers.

Health Risks associated with Mahinga kai

Water containing micro-organisms, chemicals, phytoplankton or cyanobacteria can pose a risk to health through recreational contact, drinking and gathering mahinga kai.

Mahinga kai species associated with water are fish (including tuna and inanga), kanakana shellfish (such as mussels, oysters, scallops, tuangi and tuatua) as well as seaweed and watercress.

Responsibility for Monitoring Water Quality

Regional councils like Environment Canterbury coordinate the monitoring of the various sites throughout our region and inform Community and Public Health and the territorial local authority (TLA) if contamination levels present a potential health risk.

The Territorial Local Authority places warning signs to inform the public where a health risk is identified, and takes steps to remove the contamination if possible.

Community and Public Health supports the TLAs in advising the public of the risk and ensuring that they deal with the contamination appropriately.

Be a Stormwater Superhero. Protect our waterways. Source: Environment Canterbury.



Download or order resources from the Community Health Information Centre.


Contact your local office for further information:

Ph: +64 3 364 1777

Ph: +64 3 687 2600

Ph: +64 3 768 1160

For additional information or to report water pollution, contact:

Environment Canterbury Pollution Hotline
Ph: 03 3664 663 or
0800 765 588

West Coast Pollution Hotline
Ph: 0508 800 118

Warnings to avoid some local waterways

Updated: 6th December 2023

Recreational water users are reminded to avoid contact with some Canterbury and South Canterbury waterways. Recently added warnings are highlighted in bold.

Potentially toxic algae or cyanobacteria or a high level of faecal (poo) bacteria is currently present in the following locations in the region:

  • Lake Ellesmere/ Te Waihora.
  • Lake Rotorua (Kaikoura) – this is a permanent warning.
  • Ashley/Rakahuri River at SH1.
  • Hae Hae Te Moana River at Gorge.
  • Opihi River at SH1.
  • Pareora River at Pareora Huts.
  • Selwyn/Waikirikiri River at Glentunnel.
  • Waihao River at Bradshaws Bridge.
  • St Anne’s Lagoon/ Mata Kopae.

Other popular swimming sites in Waitaha | Canterbury may also have high levels of contamination after recent rainfall. People should avoid all rivers and beaches for at least two days after heavy rain.

Find out more about the public health risks of toxic algal blooms [161KB PDF].

Find out more about keeping dogs safe from toxic algae (Environment Canterbury).

Visit the Environment Canterbury website for more information on water health warnings. Routine monitoring of waterways for summer runs from November to March each year.

LAWA: Land Air Water Aotearoa.

Page last updated: 08/12/2023

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