Freshwater quality

KEY		Public health District Health Board warnings may still remain in place when a site moves from red to green.   Click here for more information, or call Health Protection on 06 753 7798 (24 hours).
	Surveillance mode Less than 261 E. coli/100ml in single sample.
	Alert mode 261 - 550 E. coli/100ml in single sample.
	Action mode More than 550 E. coli/100ml in single sample.
	High cyanobacteria risk More than 15,000 cells/ml in single sample.

The Taranaki Regional Council undertakes microbiological water quality monitoring at a number of river sites around Taranaki during the summer months (November to March) to:

• Assess the water quality of popular bathing sites in Taranaki.
• Compare bathing water quality in Taranaki with national guidelines for contact recreational use of water.
• Monitor trends in bathing water quality over time.

The Council conducts bacteriological of samples from the freshwater sites on the map above, and additionally tests for cyanobacteria at Lake Rotomanu, the Waiwhakaiho River at Merrilands, Lake Ratapiko, Lake Rotokare and Lake Opunake.

Bacteriological

Bathing water quality is assessed according to concentrations of indicator bacteria. For freshwater river sites, this is a type of bacterium known as Escherichia coli (E. coli), which is an indicator of faecal contamination. If there is faecal contamination there is a possibility of the presence of disease-causing organisms such as bacteria, viruses and protozoa. These organisms may pose a health hazard when the water is used for recreational activities such as swimming, board riding and other high-contact activities. Poor recreational water quality can possibly cause gastrointestinal illness and respiratory health effects, such as coughs and colds.

A high concentration of the indicator bacteria means that it is more likely that disease-causing organisms are present. It does not mean that anyone swimming in the water at the time will actually be affected.

Water quality safety is assessed and reported according to the Ministry for the Environment and Ministry of Health 'Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas' revised and issued in 2003.

These guidelines categorise recreational bathing sites into one of three 'mode' categories according to single sample results of E. coli (freshwaters) and enterococci (marine waters) bacterial counts. For freshwater sites, these categories are:

The safety category is reassessed after each additional sample is collected. Sites on the maps reflect the coloured safety category and level of compliance with the guidelines at the time of the most recent sample.

In Taranaki, it is known that significant rainfall events substantially increase bacterial levels in rivers and streams (and subsequently in coastal waters along the shoreline) due to rural and urban runoff for up to several days after rainfall. This may increase numbers into the Action mode category for recreational usage. However, for trend detection purposes the Taranaki Regional Council does not sample river and beach waters within three days of any significant rainfall.

The results of the water samples collected from fresh water and coastal sites during the bathing season are updated on this site as they are received from the laboratory.

Cyanobacteria

Cyanobacteria, or blue-green algae, are very small plant-like organisms found in freshwater lakes and rivers where they can build up to very large numbers under certain conditions.

Cyanobacteria can cause skin irritation, and some species contain toxic substances and have been linked to negative effects on human and animal health.

They can cause nausea, stomach upsets, and tingling and numbness around the mouth or tips of fingers. If toxin levels are really high, involuntarily or accidentally drinking the water could result in severe liver damage.

The Taranaki Regional Council is monitoring summer cyanobacteria levels as well as bacteriological levels at Lake Rotomanu, the Waiwhakaiho River at Merrilands, Lake Ratapiko, Lake Rotokare and Lake Opunake.

There are three alert levels:

High risk will be denoted on the bacteriological water quality map with a barred circle on a purple background at the relevant monitoring site.

For more information contact the Taranaki Regional Council:

Email: info@trc.govt.nz

Phone: 06 765 7127

Fax: 06 765 5097