Summer swimming spot water quality results stable
14 July 2011
The vast majority of New Zealand’s fresh water and coastal recreation spots continue to be safe for swimming, according to a snapshot report of regional council data released by the Ministry for the Environment today.
“Overall results for last summer were pretty similar to the typical picture, with 98 percent of our monitored coastal sites and 87 percent of monitored freshwater sites generally posing a low health risk,” said Ministry Acting Information Director Neil Hurley.
Regional councils monitor selected coastal and freshwater sites for bacteria throughout summer to check they remain safe for public use. The Ministry collates this data to get an overall picture of health risks at swimming spots.
“This year the Ministry has improved the snapshot to enable a comparison of summer 2010/11 results against a ‘typical’ picture derived from five years of data from consistently monitored sites,” said Mr Hurley.
“This allows us to provide a more accurate and useful picture of typical risk and can take into account annual climatic events such as heavy rainfall or variability in how councils collect and report this data.
“From these results we can say summer 2010/11 was a bit of a mixed bag. Overall we saw slightly better results at monitored fresh water sites, while monitored coastal results were slightly worse, when each were judged against the typical picture.”
Recreational water quality can be affected by both humans and natural factors including dense bird and wildlife populations, agricultural runoff, and storm water or sewerage discharges. Wet seasons and frequent rainfall also increase the transport of bacteria and the risk of contamination.
“I applaud councils that monitor swimming spots and report the information on their websites. The Ministry for the Environment is committed to working with councils to consistently improve the way sites are monitored and how the public are informed,” said Mr Hurley.
The 2010/11 recreational water quality environmental indicator is at www.mfe.govt.nz/environmental-reporting/freshwater/recreational/index.html.
For conditions at specific monitored sites, contact the relevant the relevant regional council. The Council directory is at www.mfe.govt.nz/environmental-reporting/freshwater/recreational/local.html.
Media contact: Peter Fitzjohn ph 027 291 7158
Questions and Answers
What does this snapshot tell us?
The snapshot gives a summary of our exposure to risk from bacterial contamination at monitored freshwater and coastal sites used for swimming, surfing, diving, water skiing and sailing. Monitoring over several years indicates the ‘typical’ exposure to risk at a recreational site. This snapshot records the risk exposure over the 2010/11 summer and compares that with typical risk exposure.
What is the overall picture for summer 2010/11?
The data showed that 98 percent of about 350 monitored coastal sites generally posed a low health risk for recreation. Of these, a slightly higher proportion than usual occasionally posed a high risk (39 percent compared to 28 percent). Typically, 99 percent of our monitored coastal sites pose a low health risk.
Of about 200 monitored freshwater sites, 87 percent generally posed a low public health risk, the same as typical risk exposure. Half of these low risk sites occasionally had a high risk. This is better than typical, where 55 percent of low risk sites occasionally pose a high risk to public health.
Why are our beaches monitored?
Water contaminated by faecal micro-organisms may pose a health hazard, particularly if swallowed. In most cases the health effects are minor and short-lived but unpleasant, such as eye, ear, nose and throat infections or gastro-intestinal illnesses causing diarrhoea or vomiting. However, potentially other more harmful diseases can occur. Councils monitor beaches so they can advise the public to keep away if contamination in the water is likely to cause illness.
How is the risk monitored?
Regional councils ideally take water samples once a week over the summer (20 weeks from November to March) from selected freshwater sites and coastal sites throughout New Zealand. These are tested for the concentration of Escherichia coli (E. coli) or enterococci bacteria. These bacteria may indicate the presence of faecal material and disease-causing micro-organisms in water. All councils monitor recreational sites, however, not all monitor every week or monitor the same sites every summer.
When is a site rated as high risk?
To be rated as high risk, at least 25 percent of water samples from a site over the monitoring period are above the ‘action’ threshold for levels of bacteria.
What factors contribute to risks?
Both natural and human factors cause variations in the bacterial contamination at recreational beaches. Dense bird and wildlife populations, agricultural runoff, and storm water or sewerage discharges are all potential sources of contamination. Dry or wet seasons can affect the transport of bacteria from these sources to recreational beaches. More frequent rainfall during a wet season means these sources can affect beaches more often. Summer 2010/11 was generally extremely wet, with summer rainfall over 20 percent higher than normal in some places. There were also several large storm events in December and January.
Some sites are nearly always affected by contamination sources and are often high risk. Others are only contaminated under certain conditions, such as after heavy rainfall or following storm water discharges and are only high risk on these occasions.
What doesn’t the data tell us?
It doesn’t tell us what conditions are like over the whole of New Zealand, or what caused the contamination.
Because of variations in the way and reasons councils monitor sites, the results are not representative of environmental conditions in all our beaches. They don’t allow us to draw conclusions about regional or national environmental conditions, or how they are changing over time.
The recreational water quality environmental indicator only reports on health risk exposure from bacterial contamination. There are other reasons recreational water sites may be unsuitable (eg, algal blooms, unclear water) which are not covered by this snapshot, but which some regional councils also monitor and publicise.
Why do we compare results to ‘typical’ rather than annual results?
To get a more accurate and useful picture of typical risk, we need to consider longer-term trends rather than year-to-year changes. Annual changes in recreational water quality generally reflect short-term climatic conditions or events, because this is such a big driver in connecting contamination sources with our beaches. In addition, the fact that regional council monitoring programmes change from year to year means that identifying trends is difficult.
Why does the Ministry for the Environment collate this data?
Recreational water quality is one of 22 environmental indicators the Ministry reports on regularly as part of its national environmental reporting programme. Because we cannot continuously measure and report on every aspect of the environment, we rely on indicators which, combined, give us a picture of the environment’s overall health. The indicators cover a range of areas including air quality, waste, fresh water, land, and indigenous biodiversity. They are aligned to international environmental reporting indicators.
Are any changes to the environmental reporting indicators being considered?
The Ministry follows Statistics NZ protocols which require official statistics to use sound statistical methodology and relevant and reliable data sources that are appropriate for the purpose. A principle within this is continuous improvement to improve the quality of the statistic. We continually strive to improve the reporting of information by providing more context and greater clarity about what the statistic describes to help users to correctly interpret and use the information. We also regularly review the environmental indicators we report, to check they remain relevant and useful.
The Ministry is currently investigating the possibility of using single figures to report on air quality and river, lake and recreational water quality. The aim of these new indicators is to make it easier for us to assess current state and track trends over time, and be understood by a non-technical audience.
Another initiative is the dependable monitoring programme which aims to achieve more consistent regional monitoring and a more nationally representative data set for fresh water.
Where can I find information about my local beaches?
Check your local council’s website for information about beaches in your area.
