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.
Report confirms serious challenges for rivers
Ministry for the Environment media release: 27th April 2017
New Zealand’s rivers and lakes are under increasing pressure, according to the latest national report from the Ministry for the Environment and Stats NZ about the state of fresh water.
The report titled “Our fresh water 2017” measures the quality of our waterways; water quantity and flows; biodiversity in rivers and lakes; and the cultural health of fresh water. Key findings from the report are:
- nitrogen levels are getting worse at 55 percent and getting better at 28 percent of monitored river sites across New Zealand.
- phosphorus levels are getting better at 42 percent and getting worse at 25 percent of monitored river sites across New Zealand.
- 72 percent of the 39 native fish species are either threatened with or at risk of extinction.
- E. coli levels are 22 times higher in urban areas and 9.5 times higher in pastoral rivers compared with rivers in native forest areas.
- 51 percent of water allocated for consumptive use is for irrigation, and 65 percent of that is allocated to Canterbury.
Health Risks Associated with Contaminated Water
Water can be contaminated by human or animal excreta 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.
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.
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 are known to 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.
Contact your local CPH office for further information:
Ph: +64 3 364 1777
Fax: +64 3 379 6125
Ph: +64 3 687 2600
Fax: +64 3 688 6091
Ph: +64 3 768 1160
Fax: +64 3 768 1169
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
Toxic algae present in some Canterbury waterways
Updated 10th May 2017
All recreational water users are being reminded to avoid contact with some Canterbury and South Canterbury waterways.
Potentially toxic algae is currently present in the following locations in the region:
- Lake Ellesmere/Te Waihora
- Lake Rotorua (Kaikoura) – this is a permanent warning
Visit the Environment Canterbury website for more information. Routine monitoring of waterways during the summer season has now ended.