In this appendix we have provided a series of fact sheets about recreational water-quality monitoring. Please feel free to photocopy and distribute these to anyone wanting more information about this issue.
Beaches and rivers are important
Every weekend thousands of people flock to beaches, lakes and rivers around the country and take the plunge. The numbers soar during the summer holidays. Whether it is swimming, diving, surfing or sailing, when the sun shines Kiwis head for the beach.
A part of New Zealand culture
The Hillary Commission’s 1991 Life in New Zealand Survey looked at recreational water use and found that in the 15–18-year age groups:
- 28% had been swimming in the past four weeks
- 31% had been to the beach in the past four weeks
- 23% of males and 8% of females had been either surfing or wind surfing in the past four weeks
- 20% had been involved in water-based leisure or activities in the past four weeks.
This represents only a small slice of New Zealand’s population but is a strong indicator of how our beaches are a significant part of Kiwi culture.
Mostly clean, but ...
New Zealand’s ‘clean green image’ extends to our oceans, lakes and rivers. The perception many of us have that our coasts and freshwaters are some of the cleanest in the world is well founded. We don’t have the severity of problems facing nations such as the United Kingdom or the US. But we do have some problems.
Some of our stormwater and sewerage systems are approaching 100 years old. Combined sewerage and stormwater pipes can sometimes pump untreated human effluent into lakes, rivers and the sea, especially in urban areas. Stormwater (urban run-off) collects waste from streets, lawns and parks and deposits it in waterways. This run-off often contains animal waste. Run-off from farmland (rural run-off) collects waste from farm animals, which also ends up in rivers and finally in the sea or lakes. Animal and human waste contains disease-causing organisms that may survive in the marine environment, posing a risk to human health.
What is being done about it?
Councils monitor water quality according to guidelines developed by the Health and Environment Ministries. The purpose of monitoring is to identify risks to public health from disease-causing organisms, and to inform the public of these risks. This information allows people to make informed decisions about where, when and how they use the aquatic environment for recreational activities.
Aside from monitoring water quality, many councils have long-term plans in place to deal with ageing sewerage and stormwater systems and carry out routine inspections of these systems. Regular inspection ensures the systems are maintained to as high a standard as possible so that the waters receiving the discharge meet acceptable health criteria. But it is important to realise there has always been a health risk while in contact with waters that receive stormwater, rural run-off and sewage.
Health impacts of contaminated recreational water
There are a number of disease-causing bugs (called pathogens) that once discharged into the marine and freshwater environments can survive for some time. Every time we come into contact with waters that have been contaminated with human and animal faeces, we expose ourselves to these bugs and risk getting sick. Pristine waters are unlikely to present a health risk from these pathogens.
What does ‘risk’ mean?
The risk is of getting sick when swimming, surfing or otherwise being exposed to freshwater or seawater. The guidelines that New Zealand councils use are based on fixed levels of risk, which in turn are based on overseas guidelines (which have been confirmed by New Zealand studies). Overseas investigations have settled on a maximum acceptable level of risk for marine waters of 19 in every 1000 bathers contracting an illness. For freshwaters the accepted level of risk is 8 in every 1000 bathers contracting an illness.
Even when beaches and rivers meet the guidelines there will still be a health risk associated with recreational activities in the sea. Because scientists are not directly measuring the pathogens, it is not possible to say there is zero risk to public health, especially where there are known inputs of human and animal faeces.
If tested waters exceed the acceptable level of risk, the public is advised that the area is unsuitable for recreational activities.
What does ‘illness’ refer to?
Illnesses related to contact with recreational waters were initially thought to be confined to gastrointestinal illness such as salmonellosis. More recently Giardia, Campylobacter and Cryptosporidium have also been shown to cause gastrointestinal illness. These pathogens cause diarrhoea and sometimes vomiting associated with ‘tummy bug’ symptoms. Recent studies indicate that respiratory illnesses, such as those that cause cold and flu-like symptoms, can also result from swimming in sewage-contaminated water. Skin, eye and ear infections can also be caught through contact with marine and fresh waters.
Illnesses related to toxic substances – such as heavy metals or PCBs – are not measurable with indicator bacteria and are not covered in this fact sheet.
Stormwater, and treated and untreated sewage discharged directly into our oceans, rivers and lakes, can contain a variety of micro-organisms that can cause disease. Therefore there may be a greater risk of getting sick under certain conditions, such as:
- two to three days after rainfall
- during full immersion in water that may be contaminated with sewage or run-off
- high exposure to shallow water where there may be higher concentrations of pathogens.
There may also be a greater risk to those with reduced immunity, the elderly and the very young.
When do the guidelines not apply?
In most communities the effluent produced will contain pathogens all year round, and the guidelines councils use are designed for use under such conditions. However, when there is an outbreak of a potentially waterborne disease in the community, and where that community’s sewage is discharged directly into or close to recreational waters without adequate treatment, the guidelines that councils use are not suitable. Under these circumstances an area may be deemed suitable for recreational use based on the indicator bacteria, when in fact the levels of pathogens are elevated to a point where there is an unacceptable risk to public health.
What are councils doing?
Councils around the country monitor water quality to minimise the risk to public health. They do this by measuring the number of enterococci (indicator bacteria) in our water. They do not measure pathogens directly because the science to do this cost effectively and reliably isn’t yet available.
In addition to measuring indicator bacteria, councils look at the area surrounding the beach or river and identify potential sources of contamination. This helps councils assess the potential risk of contamination, so they can ‘grade’ recreational sites for their suitability for recreational use.
Where do I get more information?
- Councils monitor water quality and will have detailed information on specific beaches. There may be an 0800 number to call for this information.
- Local papers and radio stations may also provide information in their community bulletins.
- Signs at monitored beaches will have details about where to get more information (0800 number, radio stations, etc.) and will indicate if the beach is suitable for recreational use.
- Some council websites have information about monitoring programmes locally.
The water quality monitoring programme
Regional, city and district councils have been monitoring water quality at beaches for many years. The guidelines now used by the councils are the Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas published by the Ministry for the Environment and the Ministry of Health in 2002. These guidelines aim to establish national consistency in recreational water quality and public awareness of when there is a health risk.
Which beaches are being monitored?
The councils decide which freshwater and marine sites they will monitor before the bathing season begins. How councils decide this varies from region to region. Contact your local city or regional council to find out which sites in your region are monitored.
When are beaches monitored?
Beaches and rivers are monitored by the council on a weekly basis throughout the bathing season. The bathing season is generally from 1 November to 31 March, although this may vary depending on the local climate.
What do councils ‘do’ when they monitor water quality?
There are two parts to the council’s monitoring programme. Firstly, an overall grade for the site is worked out based on previous years’ monitoring results and an assessment of potential sources of contamination from the surrounding area. This grade gives an idea of the general condition of the site on any given day.
In addition to the overall grade, councils monitor recreational waters on a weekly basis during the bathing season. Samples are collected from monitored sites and tested for bacteria that indicate whether disease-causing micro-organisms, or pathogens, are present. The councils use the ‘traffic light’ approach of the guidelines to decide whether the beaches and rivers are suitable for swimming.
Surveillance monitoring is carried out when levels of indicator bacteria are low. Sites in surveillance mode are monitored weekly. The purpose of surveillance monitoring is to routinely check that water quality is at a level that doesn’t pose an unacceptable risk to public health.
The alert or ‘amber’ level acts as a trigger for councils to collect samples more frequently. The guidelines also recommend that when in this mode councils investigate whether there is a source of contamination causing the higher indicator levels at the beach or river.
For marine waters, when a sample taken during either surveillance monitoring or while in alert mode exceeds the action or ‘red’ mode indicator level, a second sample is taken immediately. If this also exceeds the action-level threshold the public are informed that the beach is not suitable for swimming.
For freshwater, if a sample taken during either surveillance monitoring or while in alert mode exceeds the action or ‘red’ mode indicator level, a second sample is not required to confirm the result. This is due to the potential for greater pathogen levels and their survival in freshwater. Illnesses may range from a skin infection, to a cold, to gastrointestinal disease. In action mode, sampling may increase to daily if the cause is unknown. The guidelines specify that a catchment assessment should be carried out in the surrounding catchment. This involves the council checking the sewerage and stormwater systems for leaks, illegal connections and other causes of contamination of the site. A catchment assessment can also involve investigating further up the catchment to identify contaminating activities or discharges.
How do I know if it is OK to swim?
Councils have communication strategies as part of their monitoring programmes to ensure the public are informed of a health risk at a beach or river as soon as possible. If you are concerned about water quality at beaches or rivers in your area, contact your local council for more information.
In New Zealand we are becoming increasingly aware of the potential health risks associated with swimming (and other related activities) in marine and fresh waters. Although this problem is not as severe as in many other countries, it is important that we manage the problem in the interests of public health.
When monitoring water quality at New Zealand beaches and rivers, water managers and scientists are interested in the number of disease-causing pathogens present. It is impractical to measure the pathogens directly, so indicator bacteria are used to alert water managers to possible health risks presented by the pathogens.
What are indicator bacteria?
In the case of the recreational water-quality guidelines, the indicator bacteria are enterococci for marine waters and E. coli for freshwaters. These bacteria occur naturally in the gut of humans and animals, including mammals, birds, fish and reptiles. The indicator bacteria themselves do not pose a significant risk to human health. Rather, they indicate the presence of faecal material, which contains disease-causing pathogens. It is the number of enterococci or E. coli per 100 mL of water that is measured and on which the guideline levels are based.
What are pathogens?
Pathogens are microscopic organisms that cause disease in humans and animals. There are many different kinds. Some of the more widely known are Campylobacter, Salmonella, Giardia, Cryptosporidium, and viruses that cause diarrhoea and cold and flu-like symptoms. These pathogens are present in faeces and may enter our waterways through untreated sewage discharges, and from leaky sewerage pipes, septic tanks, stormwater and rural run-off.
When do the guidelines not apply?
In most communities the effluent produced will contain pathogens all year round, and the guidelines councils use are designed for use under such conditions. However, when there is an outbreak of a potentially waterborne disease in the community, and where that community’s sewage is discharged directly into or close to recreational waters without adequate treatment, the guidelines councils use are not suitable. If the guidelines are used under these circumstances a beach or river may be deemed suitable for recreational use based on the indicator bacteria, when in fact the levels of pathogens are raised to a point where there is an unacceptable risk to public health.
Indicator bacteria tell us about the likelihood of there being pathogens present in the water. We don’t use indicator bacteria to measure the likelihood of there being toxic contaminants or harmful poisons such as heavy metals, poly-aromatic carbons or PCBs.
The sources of contamination in waters used for recreation
This fact sheet discusses the sources of bacteria and pathogens in waters used for recreation that pose a risk to human and animal health.
Sewage from many communities is collected via a network of pipes and pumped to a central facility, where it is treated before being discharged to the environment. Sewage consists mostly of water, but also contains organic material and micro-organisms. There are a number of factors that can cause sewage to enter the environment before completing its journey through the treatment facility. The main ones include:
- broken or leaky pipes – these can be caused by ageing pipes, construction activities or road works
- overflows, during heavy rainfall – the treatment facility may not be able to cope with the volumes of water and sewage entering the system, so pumps are turned off and sewage is discharged directly to the environment. This is made worse where houses have stormwater illegally connected to wastewater. Also, some older sewerage systems do not have completely separated sewage and stormwater pipes. During high rainfall, stormwater (urban run-off) can enter the sewerage system and cause sewage to overflow into the stormwater pipes. Sewage is then discharged directly to the environment
- emergency overflows – these can also occur periodically during maintenance of sewerage systems.
There are also other sources of sewage.
- Some older properties, especially baches, are still connected to a septic tank. Where these have deteriorated they leak contaminated water into the groundwater system. This contaminated water then ends up in waterways and eventually at the beach.
- Some boaties discharge their waste directly into the sea, without treatment.
The cost of upgrading much of the country’s ageing pipes to cope with our increasing population is estimated to be several billion dollars. It is anticipated that these upgrades will be spread over several decades.
Rainwater collected from roofs, driveways, roads, carparks and other sealed surfaces is piped directly to rivers, lakes and the marine environment without treatment. During its travels stormwater collects a number of nasties along the way. This includes waste from domestic animals, which collects on footpaths, gutters and lawns. This contaminated water is washed into the stormwater system during rainfall and ultimately ends up on our beaches. Animal waste collected in stormwater contains disease-causing organisms that can affect human health. These pathogens can cause colds, flu, respiratory illness, gastrointestinal illness and skin, eye and ear infections.
Farm run-off can add significantly to the contamination of waterways. Apart from farm oxidation ponds, which have been shown to contain high levels of bacteria and pathogens, a large amount of animal waste ends up on the paddock. Depending on a number of factors – including distance to the nearest stream, rainfall intensity and stock numbers – faecal material ends up in rivers and streams, which ultimately discharge to the sea. Where stock have access to streams and rivers for drinking water, excrement may be deposited directly into the water.
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