Monitoring
The Environmental Health Directorate, in partnership with many Local Government authorities, and some other stakeholders, collect water samples to test for bacteria, and carry out health assessment activities at a number of popular waterways commonly used for swimming, surfing and skiing in WA.
Please refer to the following factsheets for specific details regarding the number of bacterial water samples that the Department of Health and Local Government Authorities will be collecting this swimming season. The factsheets also provide information regarding Local Government Authority sanitary inspection activities for assessment of faecal pollution risks in relation to each popular recreational site.
Frequently asked questions
Why monitor?
Water is monitored for bacteria so we can:
- make sure the water is safe to swim in and or recreate
- classify water bodies to help you decide where you want to swim
- issue warnings during pollution events
- identify bacterial pollution sources
- look for long-term bacterial trends
What are the sources of bacteria in water, and what are the potential health risks?
Bacteria in water can come from a number of sources including farming activities, domestic animals, human effluent and wildlife. Swimming and/or swallowing water contaminated with high levels of bacteria can put you at risk of illness such as gastroenteritis, skin irritations or ear and eye infections. This is why it is important to be aware of the common causes for high levels of bacteria in natural waterways so you can avoid swimming and other similar recreational activities during these times.
Which waterways are monitored?
Those popular recreational waterways which are monitored are located within the following local government jurisdictions or other commonly known areas within WA:
When are water monitored?
In general, recreational waterways are monitored once every fortnight from November to May when people usually go swimming. Monitoring during winter is not considered necessary as majority of the public do not go swimming during these times.
What do we test for?
Water samples are tested in a laboratory for a group of bacteria called Enterococci. Enterococci are commonly found in the stomach of warm blooded animals and humans. High levels of these bacteria can help indicate a decrease in water quality for swimmers. Although Enterococci are not harmful themselves, they can indicate the possible presence of harmful microorganisms such as bacteria, viruses and protozoa.
What guidelines are sampling results compared against?
In October 2005 the National Health and Medical Research Council (External link) (NHMRC) released the Guidelines for Managing Risks in Recreational Water. These guidelines were re-published in 2008 and utilise a new approach to managing recreational water issues by looking at the bacteria levels in the water as well as everything else in and around the water such as storm water drains, septic tanks and animals that may play a role in decreasing the bacterial water quality.
The bacterial water quality at a given beach or site is assessed for the purposes of the above Guidelines according to the 95th percentile of the numbers of Enterococci recorded at that site. The Department of Health has produced an easy-to-use template “(the Enterotester)” for calculating 95th percentile statistics for these bacteria, standardised for comparison with the 95th percentiles used in the Guidelines. The Enterotester template is packaged together with ‘Simple Step by Step Instructions’ that have been developed to assist the user to work through this template.
All this information is combined to assign a beach grade to the water so you as a water user can have a better understanding of the bacterial water quality and make a more informed decision about where and when you would like to go swimming.
Refer to the above mentioned ‘Applying the NHMRC Guidelines for Managing Risks in Recreational Water’ guidance note for further information.
What do beach grades mean?
There are five beach grades – Very good, good, fair, poor or very poor – which have been placed into three different colours, green, amber or red. Green represents the safer areas to swim, whilst red represents the areas of higher risk. The grades are defined below:
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Very Good: Water quality is considered safe for swimming at all times. Water quality results have been consistently of a high standard and there are very few potential pollutant sources which have been identified at this beach.
Good: Water quality is considered safe for swimming most of the time. Water quality results have been good on nearly all occasions and there are few potential pollution sources which have been identified at this beach.
Standard warnings should be followed such as avoiding swimming for up to 3 days after heavy rainfall (e.g. >10mm) in river and estuarine waters due to the possible presence of stormwater pollutants. |
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Fair: Water quality is considered generally safe for swimming. although water quality results have at times shown elevated levels of bacteria, mostly due to animal pollutant sources (e.g. bird faeces) and from pollutants flushing into the water from rainfall.
Swimming should be avoided during and for several days following heavy rainfall (e.g. >10mm) and if the water is discoloured. |
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Poor: Water quality may not always be safe for swimming. Water quality results have a tendency to be affected by elevated bacterial levels, mostly during and following rainfall events, or due to animal pollutant sources (e.g. bird faeces). Low dilution, tidal movement, wind direction and stormwater pollution may also assist disease causing microorganisms e.g. bacteria and viruses to survive longer in these waters. Putting your head under the water when swimming should be avoided.
Swimming should be avoided during and for at least a week following heavy rainfall (e.g. >10mm) and if the water is discoloured, as there may be a higher risk of illness if you swallow the water during these times Young children, the elderly and those with compromised immunity may be particularly vulnerable.
Activities such as canoeing, boating and fishing are still suitable.
Very Poor: Water quality is generally poor. Avoid swimming at these locations, as there may be direct discharges of faecal material. Permanent warning signs may be erected at the beach stating that swimming is not recommended. |
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New Sample Site: Insufficient water quality or site information is available to assign a bacterial risk classification.
The local government environmental health service may have commenced bacterial water quality monitoring at this site, however a site assessment is still required.
Standard warnings should be followed such as avoiding swimming during and for several days following heavy rainfall (e.g. >10mm) and if the water is discoloured.
Please also consider low water dilution levels, tidal movement, wind direction and the potential for stormwater pollution before making a decision to swim at this site |
How often are beach grades assigned?
Beach grades are assigned each year as we start to get a better understanding of the bacterial water quality at our beaches. At the moment all grades are temporary because they are based on limited bacterial data or incomplete site assessment information.
PLEASE NOTE: This means that the temporary grades may be deliberately conservative and categorise water quality into a higher risk classification.
For further information on bacterial water quality, please refer to specific beach grades for popular swimming and recreational locations throughout WA, or contact the Environmental Health Directorate on +61 8 9388 4999 or email ehinfo@health.wa.gov.au.
Relevant Publications
Fact sheets
Forms & Templates
Guidelines
Guidance Notes
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