Swimming

​We monitor bathing water quality at both marine and freshwater bathing sites over summer each year.

The main health risk associated with bathing is posed by disease-causing microorganisms such as viruses, bacteria and protozoa. Increases in these are the result from human or animal faecal matter finding its way into water.

The major sources are sewage, industrial discharges, and runoff from agricultural land. In some areas water quality is also affected by septic tanks and discharges from boats.

What is being done?

The main health risk associated with bathing is posed by disease-causing microorganisms such as viruses, bacteria and protozoa. Increases in these are the result from human or animal faecal matter finding its way into water. The major sources are sewage, industrial discharges, and runoff from agricultural land. In some areas water quality is also affected by septic tanks and discharges from boats.

During summer (December to March), Environment Southland regularly monitors 13 marine bathing and 7 freshwater bathing sites The bathing water quality is assessed according to concentrations of indicator bacteria which  do not cause disease themselves, but signal the potential presence of disease-causing pathogens. A high concentration of the indicator bacteria means that it is more likely that disease-causing organisms are present, and therefore a potentially higher health risk. However, it does not mean that anyone swimming in the water at that time will actually be affected. Councils do not measure the pathogens directly because the technology to do this is cost-effectively or unreliable.

The indicator used depends if it is a freshwater or marine site. In freshwater we measure levels of bacteria known as Escherichia coli (E. coli), whereas we measure enterococci bacteria at marine sites.

Southland's recreational bathing water quality is assessed and reported according to national guidelines set by the Ministry for the Environment and Ministry of Health. Access these guidelines can be accessed on the Ministry for the Environment website.

Environment Southland prepares a monitoring plan for 'Recreational Bathing and Shellfish Gathering Waters in Southland', in collaboration with Public Health South, Southland District Council and Invercargill City Council. The monitoring results automatically go to the health authorities (Public Health South, and the territorial authorities) who are responsible for informing the public of health risks associated with contaminated bathing and shellfish growing waters.

How do I know if it's safe to swim?

The national guidelines for microbiological water quality categorise recreational bathing sites into a three different 'modes' (green, amber, red) according to the results of indicator bacteria counts. This 'traffic light' approach helps inform the public on whether the water quality of a site is suitable for swimming and other water-based recreational activity.

Check out the latest results from our weekly summer monitoring of Southland's bathing sites on our online maps.

ModeMarine (enterococci/100mL)Freshwater(E. coli/100mL)
Green/Surveillance
(minimal health risk)
No single sample greater than 140No single sample greater than 260
Amber/Alert
(health risk may have increased)
One single sample between 141 and 280One single sample between 261 and 550
Red/Action
(significant health risk)
Two consecutive single samples greater than 280One single sample greater than 550

Environment Southland uses two ways of assessing and advising the water quality risks to bathing. These are:

  • weekly monitoring of bathing water quality over summer (the latest results are shown in the online map);
  • incorporating long-term water data and catchment use to give an overall Suitability for Recreation Grading.

When am I most at risk?

Under certain conditions there is a greater risk of getting sick in the course of recreational water-based activities.

Swimmers can reduce their risk to illness by:

  • swimming away from stormwater outlets
  • swimming away from streams and areas with possible runoff from intensive agriculture
  • not swimming during and for up to two days after heavy rainfall

There is potentially a greater risk to those with weakened immunity, such as the very young, and the elderly.

Suitability for Recreation Grades

As well as measuring bacteria levels, we allocate a grade to beaches according to the suitability of the water for recreation (Suitability for Recreation Grade, SFRG). The grades are based on faecal contamination risk factors within the catchment (e.g. intensive agricultural use in immediate catchment), and levels of indicator bacteria, based on data that has been collected over time. This grade gives an overview on how safe it is to swim in a particular location. Beaches are graded as: Very Good, Good, Fair, Poor, Very Poor. The risk of becoming sick from swimming at a beach increases as the beach grading shifts from Very Good to Very Poor.

Downloads / reports

Recreational Waters of Southland
This report summarises the results of Environment Southland's 2012/13 microbial monitoring programme, which monitors the public health risk from contact recreation at 11 marine beaches, 13 rivers and lakes, and 8 shellfish gathering sites in the region.

Download the report Recreational Waters of Southland.

Recreational Bathing Survey 2015
This report includes the findings from a survey conducted across Southland over the summer of 2015. The survey's aim was to find where people undertake recreational activities, what activities are being carried out, what kai is being collected, what problems are being experienced, and whether the recreational bathing programme is delivering to the public needs.

Download the Recreational Bathing Survey 2015.

More information

For further information on health risks:

​OrganisationPosition​Postal Address​Phone​
​Southland District Council (also for Gore District Council)Environmental Health Officers15 Forth Street
PO Box 903
Invercargill
(​03) 218 7259
​Invercargill City CouncilEnvironmental Health OfficersCivic Administration Building
101 Esk Street
Private Bag 90104
Invercargill
(​03) 211 1777
​Public Health SouthCo-ordinator Health Protection92 Spey St
PO Box 1601
Invercargill
(​03) 211 0900
​Medical Officer of HealthC/- Public Health South​N/A​(03) 211 0900

For further information on environmental monitoring:

​OrganisationPosition​Postal Address​Phone​
​Environment SouthlandCoastal ScientistCorner of North Road and Price Street
Waikiwi
Private Bag 90116
Invercargill
0800 76 88 45


Page reviewed: 04 May 2016 12:28pm