Research and Monitoring Programs: Further Monitoring
In 2000, we started an additional long-term monitoring program to assess recreational water quality of marine waters near the south east outfall. The decision to start this program followed a Health Impacts Study by Monash University. The 1999 study found that surfers and swimmers were at no additional risk of contracting disease from the area compared with other beaches studied.
Monash University did a second study in 2001 to review the results of the monitoring program. The Department of Health has advised Melbourne Water that based on the two studies by Monash University, and a review of data from the microbiological monitoring program, "there is no significant microbiological health risk to swimmers or surfers."
In February 2006 the Department stated "...the Department of Health is of the view that the South Eastern Outfall does not make Gunnamatta Beach unsuitable for recreational use."
The methodology used for this recreational assessment program is the National Health and Medical Research Council (NHMRC) Guidelines for Managing Risks in Recreational Waters (2005). The Guidelines use Enterococci as the best bacterial indicator for measuring faecal contamination in the marine environment.
This methodology combines an assessment of the potential sources of contamination at a beach with the monitoring of Enterococci data at various recreational points over an extended period. In accordance with NHMRC Guidelines we have set an assessment period of 12 months. The recreational water classifications based on the assessment are very poor, poor, fair, good, or very good.
Enterococci levels are sampled at 18 sites in the swim and surf zones. There are six sites in the swim zone (sites 1-6), six sites 800 metres from shore in the surf zone (sites 8-13), and six sites 400 metres from shore in the surf zone (sites 8X-13X: these sites were added to the program in 2004-2005). There is also a reference site (site 14).
Sampling Sites
Three samples (A, B and C) of 500ml (2 cups) each of water are taken by an independent testing laboratory, Ecowise, at each site for testing (i.e. 54 samples per testing cycle). In summer (December-March), testing takes place fortnightly, while during the cooler months, testing is completed monthly.
Results of the samples are analysed over 12 months to give a 95th percentile result. (For example, if the 95th percentile result was 112, then 95% of the Enterococci count numbers are less than or equal to 112 per 100ml.). This 95th percentile result for each site represents the Microbial Assessment Category.
After the end of each financial year, raw data is available to download at the bottom of this page. Annual results are also published in our 2008-2009 Sustainability Report.
Downloads
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