What is being monitored?
Biological Indicators
Monitoring for bacteria
The program monitors the levels of enterococci, a group of bacteria recommended as the best indicator of microbiological water quality in marine environments.
With our current level of understanding of Port Phillip Bay during winter months it is not possible to predict bacterial levels at any given time. This program provides the latest information available on bacterial levels at beaches within the bay.
View results from bacterial monitoring
The National Health and Medical Research Council (NHMRC) suggests that levels above 500 organisms per 100ml for recreational waters present a risk to swimmers and so EPA uses this level as a trigger for further review and sampling. As per standard Beach Report protocols, the data will be reviewed in the light of recent weather and if a second sample is above 500 organisms per 100ml, EPA will investigate.
Monitoring for algae
The program monitors for algal species that may be potentially harmful for human health, such as blue-green algae species that can produce toxins. Algal levels are measured by identifying individual algal species and then each species is reported as cells per litre.
These algal species are all microscopic (not able to be seen by the naked eye) except during ‘bloom’ (a sudden increase in numbers).
We compare the algal cell counts against guidelines published by the National Health and Medical Research Council (NHMRC 2008). EPA also relies on the expertise of scientists to identify potentially toxic species specific to Port Phillip Bay.
Swimmers who come in contact with toxic algal species can become ill from ingestion or develop skin complaints. The focus of the monitoring and assessment is about potential short-term exposure rather than long-term exposure.
The NHMRC guidelines indicate that, if toxic algal species are found at certain levels, an investigation should commence to isolate the species and assess the toxicity of the compounds in the algae. Not all potentially toxic algae have toxic chemicals in them at all times, or even have the same chemicals over time.
View results from algal monitoring
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Noctiluca is a common algae in Port Phillip Bay that often blooms in summer. May cause skin irritations in some individuals. |
Monitoring for chemicals
The program monitors levels of nine common metals and seven common organic chemicals found in the Port Phillip Bay and the lower Yarra River. These are:
- Metals: arsenic, cadmium, chromium, copper, lead, manganese, nickel, mercury and zinc.
- Organic chemicals: endosulfan, aldrin, dieldrin, chlordane, DDT, heptachlor and heptachlor epoxide, hexachlorobenzene and PCBs.
They are all measured and reported in micrograms per litre (ug/L).
View monitoring results for metals and organic chemicals
Both filtered and unfiltered samples are analysed for metals. In the first instance the unfiltered samples are used for comparison with relevant guidelines. If high levels of metals are found, comparing the results from these two samples will assist in assessing water quality.
The chemical results are compared against recognised guidelines published by the National Health and Medical Research Council (NHMRC 2008). For more information visit our Guidelines web page.