Protecting the quality of local recreational water

Te Mana Ora | 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

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.

Swimming or other activities 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.

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.

• Find out more about recreational water quality, including what health warning signage to look out for [113KB PDF].

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.

• Find out more about the public health risks of toxic algal blooms – updated November 2023 [140KB PDF].
• Learn about the causes of increased algal growth at the Rakaia river mouth this summer (Environment Canterbury).

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.

• Find out about the public health risks around mahinga kai gathered from water [131KB PDF].
• Get food safety tips for shellfish including information on Vibrio parahaemolyticus (Ministry for Primary Industries).

Kai gathering activities have significant risks. Twenty-one people drown and more than 2,500 people are injured every year while gathering kai. These fatalities reveal a disproportionate impact Māori and Asian New Zealanders communities, and 70 percent of fatalities are men aged 45 and over. So make sure you prepare well and stay well by:

• checking the seaworthiness and safety of your boat;
• servicing your equipment to prevent accidents or failures;
• being in good shape and physical health so you can handle the intensity of the activities; and
• gathering with at least one other person so you have help immediately available if anything goes wrong.

• Get more recreational water safety advice from Water Safety NZ.

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.

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

• Find out the latest on recreational water quality in Canterbury (Environment Canterbury).
• Find out the latest on recreational water quality on the West Coast (West Coast Regional Council).
• Read about the experience of Canterbury students doing summer water monitoring (Environment Canterbury).

Documents

• LAWA Lake Quality National Picture Summary – updated annually.
• LAWA River Water Quality National Picture Summary – updated annually.

• Aotearoa New Zealand Cyanobacteria Guidelines in Recreational Freshwaters (Ministry for the Environment 2025).
• National Policy Statement for Freshwater Management: Amended October 2024 (Ministry for the Environment).
• The Environmental Case Management of Persons Exposed to Harmful Algal Bloom and Cyanobacteria: Guidelines for Public Health Officers (Health NZ 2024).
• 2023 Christchurch Surface Water Quality Report (Christchurch City Council 2024).
• National Estuary Monitoring Protocol (Ministry for the Environment 2024).
• Our freshwater 2023 (Ministry for the Environment).
• Our marine environment 2022 (Ministry for the Environment).
• New Zealand coastal water quality assessment 2021 (Ministry for the Environment 2022).
• Impacts of climate and freshwater policies: Literature review (Ministry for the Environment 2020).
• Assessment of anatoxin levels in the water of rivers affected by Phormidium blooms (Ministry for the Environment 2020).
• Review of the New Zealand Guidelines for Cyanobacteria in Recreational Fresh Waters (Ministry for the Environment 2018).

Downloads

• Cryptosporidium and Giardia.

Links

• Environment Canterbury (ECan).
• West Coast Regional Council (WCRC).
• Ministry for the Environment.