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.
Shellfish now safe to collect and eat in Canterbury
Updated 10th February 2017
Community and Public Health wishes to advise that the public health warning not collect shellfish in the Canterbury region has been removed.
The Ministry for Primary Industries (MPI) stated that ongoing testing of shellfish has found the levels of toxins causing Diarrhetic Shellfish Poisoning to be below the safe levels. Warning signs throughout the region will be taken down in the coming days.
“This is great news for those of us who love collecting and eating our own kaimoana. It has been a long wait since the warning was originally issued (13th October 2016) and lovers of seafood in Canterbury should be commended for heeding the warnings for so long,” says Canterbury Medical Officer of Health Dr Alistair Humphrey.
Mussels, oysters, tuatua, pipi, toheroa, cockles, scallops, catseyes, kina (sea urchin) and all other bivalve shellfish are now safe to eat.
The following symptoms of Diarrhetic Shellfish Poisoning usually appear within half an hour of ingestion and last for about 24 hours:
- nausea, and
- abdominal cramps.
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 21st February 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 Forsyth/Te Roto o Wairewa
- Lake Pegasus
- Lake Rotorua (Kaikoura) – this is a permanent warning
- Cust River near Skewbridge Road
- Hurunui River at State Highway 7 (including the swimming hole behind the Balmoral campground)
- Te Nga Wai River at Te Nga Wai Bridge (near Pleasant Point)
- Opihi River at Saleyards Bridge (near Pleasant Point), near State Highway 1, and near the Waipopo Huts
- Selwyn/Waikirikiri River at Glentunnel and Whitecliffs Domain
- Waihao River near Bradshaws Bridge