Recreational water quality in New Zealand
Indicator update
October 2012; INFO 653
What this indicator update tells us
- Most of our popular coastal swimming spots are fine for swimming most of the time.
- There are many freshwater swimming spots which should be avoided.
This indicator update gives a summary of the suitability of the freshwater and coastal beaches we choose for recreation. It uses data published by regional and district councils to report on recreational water quality at a national scale. This is the first time we have used ‘beach grades’ – this new method provides information about typical conditions. It focuses on the suitability for swimming at popular swimming spots, and does not give a comprehensive picture of the overall state of New Zealand’s waterways. Our new methodology means we cannot assess trends this year but it will allow us to better measure future change.
This indicator update cannot tell you whether it is safe to swim today at a particular spot and does not replace the site-specific information available on regional and district council websites which can help people understand the likely health risk when deciding whether to go swimming.
Grades in 2012
A total of 210 freshwater beaches and 248 coastal beaches used for recreation have been assigned a beach grade based on monitoring data acquired over five consecutive summers (including the 2011–12 summer). The results presented here are based on these sites.
Other recreational beaches are being monitored but do not have sufficient data to be assigned a beach grade. Almost all regions undertake their own seasonal recreational water quality monitoring. Contact regional and district councils for more information about current conditions and specific monitoring sites.
Figure 1: Suitability for recreation grades at freshwater and coastal beaches used for recreation
Note: see the ‘What are beach grades?’ box below for a description of the beach grades. Data is collected by regional and district councils and collated by the Ministry for the Environment.
Read a description of this figure
The bar graph shows the proportion of monitored freshwater and coastal beaches used for recreation and graded in 2012 that fall into each beach grade: for freshwater recreational sites, 21 per cent have been graded as ‘very poor’; 24 per cent have been graded as ‘poor’; 24 per cent have been graded as ‘fair’; 15 per cent have been graded as ‘good’; and 17 per cent have been graded as ‘very good’. For coastal recreational sites, 3 per cent have been graded as ‘very poor’; 13 per cent have been graded as ‘poor’; 25 per cent have been graded as ‘fair’; 42 per cent have been graded as ‘good’; and 18 per cent have been graded as ‘very good’.
What are beach grades?
Beach grades describe the likely condition of a beach that may be used for recreation during summer. They are based on an assessment of potential sources of faecal contamination. There are five different grades that can be assigned to a coastal or freshwater beach:
- very good – considered satisfactory for swimming at all times
- good – satisfactory for swimming most of the time. Exceptions may include during or following periods of high rainfall
- fair – generally satisfactory for swimming, though there are many potential sources of faecal material. Caution should be taken during or following periods of high rainfall, and swimming avoided if water is discoloured
- poor – generally unsuitable for swimming, as indicated by historical water quality results. Swimming should be avoided, particularly by the very young, the very old, and those with compromised immunity
- very poor – should be avoided for swimming. People are exposing themselves to high risk of illness when using these beaches for recreation, and signage may be erected at these sites to warn people that swimming is not recommended.
Of the 458 monitored beaches that were graded in 2012:
- 17 per cent of freshwater beaches and 18 per cent of the coastal beaches were graded as ‘very good’. A further 15 per cent of freshwater and 42 per cent of coastal beaches were graded as ‘good’
- 24 per cent of freshwater beaches and 25 per cent of coastal beaches were graded as ‘fair’
- 24 per cent of freshwater and 13 per cent of coastal beaches were graded as ‘poor’
- 21 per cent of recreational freshwater beaches and 3 per cent of coastal beaches used for recreation were graded as ‘very poor’.
This year’s results cannot be compared with last year’s because we have changed our reporting method to one which is clearer and gives a better indication of health risk. The categories that were used to grade freshwater and coastal beaches are not comparable with those that we have used in previous years. However, this new way of reporting will allow us to monitor change more effectively from this year on.
Why have we moved to reporting beach grades?
- They are scientifically sound – The methodology, outlined by the guidelines for contact recreation, was developed in collaboration with the Ministry of Health. It was developed by trialling international epidemiological studies and guidelines and adapting them to the New Zealand context. This methodology follows World Health Organisation guidelines for water quality monitoring. We have consulted with councils, Crown research institutes and academics on using this method of reporting at the national level.
- They are more reliable – Previously, our reporting on recreational water quality used an interim method which assessed risk based on one summer’s worth of data. Results were highly dependent on weather events for that particular year. Beach grades give a more reliable assessment of typical water quality for a site, as they are based on five years’ of data which reduces the influence of weather conditions on the results. Beach grades also incorporate a sanitary inspection of the area surrounding the site which identifies potential sources of faecal contamination. For more information, see the ‘How beaches are graded’ section below.
- They are easier to interpret – Beaches now have five grades (‘very good’ to ‘very poor’), as opposed to three risk categories used previously. The grades are less ambiguous and provide a clearer picture of the typical health risk of using a particular beach on any given day. Using grades to report nationally is more consistent with regional and district councils’ recreational water quality reporting.
- We can measure change better – The fact that beach grades are less influenced by short-term weather conditions means they can be used to show genuine change in water quality over time.
Figure 2: Map of suitability for recreation grades at beaches around New Zealand
Note: the white dots show the sites that have been monitored but have not been assigned a beach grade as they do not have sufficient data. The coloured dots show the sites that have been graded in 2012. See the Recreational Water Quality 2012 data (XLS, 31 KB) or (PDF, 208 KB) used in this indicator update. Data is collected by regional and district councils and collated by the Ministry for the Environment.
Read a description of this figure
This figure is a map of New Zealand showing the location and 2012 beach grades for freshwater and coastal beaches used for recreation.
How beaches are graded
The guidelines for contact recreation published by the Ministry for the Environment recommend that beaches used for recreation are identified and prioritised for monitoring the presence of risk factors in the catchment based on potential sources of faecal contamination. This enables regional and district councils to cost-effectively identify and manage public health risk, but means that recreational monitoring results are not representative of overall water quality in New Zealand. In addition, regional results are not directly comparable due to variations in the way beach grades are determined. The Ministry for the Environment is working with regional and district councils to ensure a standardised methodology is used across regions.
There are two components to calculating a beach grade:
- A catchment inspection that identifies the risk factors that might make the beach susceptible to faecal contamination. Both natural and human factors are considered to be as potential sources of microbiological contamination, such as agricultural run-off, stormwater or sewage discharges, and dense bird or other wildlife populations
- Water samples collected weekly over five summers (usually from November to March). The samples are tested for bacteria that are indicators of faecal contamination and thus of the presence of disease-causing micro-organisms. The indicator bacteria used are Escherichia coli (E. coli) in fresh water and enterococci in coastal waters.
While beach grades provide information about the typical state of a beach, regional and district councils also use weekly monitoring to inform the public of more immediate health risks when measured bacteria concentration exceed ‘action thresholds’. These action thresholds are based on levels of risk drawn from international guidelines confirmed by New Zealand studies.
There are other reasons why beaches may be unsuitable for recreation, such as algal blooms or poor water clarity. These are not covered by this indicator update, but many regional and district councils monitor and report on other risks to the public.
Health risks of faecal contamination
Water contaminated by faecal micro-organisms poses a health hazard, particularly if swallowed. In most cases the health effects are minor and short-lived, such as gastric-intestinal illnesses with symptoms like diarrhoea or vomiting, and infections of the eye, ear, nose and throat. However, there are other potentially more harmful diseases such as giardiasis, cryptosporidiosis, campylobacteriosis and salmonellosis. Hepatitis A can also be contracted from contaminants in the water and can lead to long-term health problems.
Anyone can be affected from exposure to contaminated water, but small children, the elderly, and people already weakened by illness or fatigue are more vulnerable.
Last updated: 10 October 2012
