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Melbourne Water

Melbourne's water
storages are currently

34.7%

Research and Monitoring Programs

Keeping a close watch

We monitor every aspect of the sewage treatment process, from the moment the sewage arrives at the plant, to when it is discharged as fully treated effluent into Bass Strait.

Senior Process Engineer, Dr Deepak Joshi, has 17 years experience in the field and emphasises the importance of the monitoring program: "Every day we are focused on the process that has been established to ensure the highest possible standards of treatment. Our on-site laboratory is staffed by two people, their singular focus is checking and cross-checking the results we’re getting."

"The monitoring process means keeping a close eye on what we call the settling process and examining the bacteria used in the treatment process in microscopic detail. By looking at things in this precise way we can make sure that, when the treated effluent leaves the plant, the process here has taken it to its optimal level."

Water quality monitoring

EPA Victoria requires that recreational water quality be assessed through weekly E. coli monitoring at six shoreline points, including Gunnamatta Beach, St Andrews Beach and Boags Rocks. Testing is undertaken by a NATA (National Association of Testing Authorities) accredited independent laboratory, Ecowise.

Since February 2005, we have also been monitoring for Enterococci. Enterococci is recognised by the World Health Organization (WHO) as the most appropriate bacterial indicator for measuring faecal contamination in the marine environment. The results are published on the website as they become available.

Water quality monitoring is undertaken for environmental compliance. The results for 2005 found that the water quality met EPA health-based water quality objectives. The Department of Human Services has advised that the South Eastern Outfall does not make Gunnamatta Beach unsuitable for recreational use.

A study by Monash University on the health effects of ocean outfalls concluded that surfers and swimmers were at no additional risk of contracting disease from the area compared with other beaches studied. As Gunnamatta is an ocean beach, swimming is only recommended in the area patrolled by the Gunnamatta Surf Lifesaving Club.

Understanding water quality monitoring results

The nature of microorganisms means that results can vary significantly from sample to sample and day to day. For this reason, assessment is not made on individual samples. Assessment over a period more accurately reflects the beach condition. Fluctuations in microorganisms can be the result of factors such as wind conditions, boats and bird activity as well as changes that may occur to the sample after it has been collected.

EPA Victoria’s State environment protection policy (SEPP), Waters of Victoria, issued in June 2003 specifies recreational water quality objectives for both E. coli and Enterococci. The E. coli and Enterococci median (5 samples in 30 days) and the Enterococci 75th percentile (11 samples in 60 days) need to be less than the SEPP objectives outlined in the table below.

Primary Contact
  E. coli org/100ml Enterococci org/100ml
  Median of five samples
in 30 days		 Median of five samples
in 30 days		 75th percentile 11 samples
in 60 days
SEPP Objectives <150 <35 <150
The sites around the South Eastern Outfall where samples are taken

Median = The middle value of a set of numbers, when they are sorted in ascending order.

75th percentile = This is the result for which 75% of the results are lower and 25% are higher.

Most Recent Results

E.Coli
Sampling point Site number Date updated Median E.coli
(orgs/100mL)
five samples
in 30 days
Boags Rocks east 1 03-Mar-2010 0
Boags Rocks west 5 03-Mar-2010 2
Gunnamatta beach - east 4 03-Mar-2010 0
Gunnamatta beach - middle 3 03-Mar-2010 0
Gunnamatta beach - west 2 03-Mar-2010 0
St Andrews beach 6 03-Mar-2010 0
Enterococci
Sampling point Site number Date updated Median Enterococci
(orgs/100mL)
five samples
in 30 days		 75th percentile Enterococci
(orgs/100mL)
11 samples
in 60 days
Boags Rocks east 1 03-Mar-2010 0 1
Boags Rocks west 5 03-Mar-2010 0 3
Gunnamatta beach - east 4 03-Mar-2010 0 0
Gunnamatta beach - middle 3 03-Mar-2010 0 2
Gunnamatta beach - west 2 03-Mar-2010 0 0
St Andrews beach 6 03-Mar-2010 0 0

Click here to view our archive of past results.

Annual summary results are provided in the Melbourne Water 2006/07 Social and Environment Report and any non-compliance with EPA limits is reported to the EPA and results are published in Melbourne Water’s annual report to the EPA (PDF 354kb).

Further Monitoring

In 2000, Melbourne Water commenced an additional long-term monitoring program to assess recreational water quality of marine waters near the south east outfall. This is a program undertaken in addition to the compliance monitoring program required by EPA Victoria.

The decision to start the recreational assessment program followed a Health Impacts Study undertaken 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 conducted a second study in 2001 to review the results of the monitoring program. The Department of Human Services 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 "…DHS 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 most appropriate 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 Melbourne Water has 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 2004/05). 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 Melbourne Water's Social and Environment Report.

The nature of microorganisms means that numbers can vary significantly from sample to sample and day to day. For this reason, the NHMRC guidelines specify that water quality assessments not be made on the basis of individual samples. Assessment over a period more accurately reflects the beach condition. Fluctuations in microorganisms can be the result of factors such as wind conditions, boats and bird activity as well as changes that may occur to the sample after it has been collected.

Recreational Water Classification

Based on the level of treatment provided at the Eastern Treatment Plant and the outfall type, the assessment of potential sources of contamination results in a risk potential of 'very low'.

Based on this risk potential the Recreational Water Classifications for various microbial assessment categories (based on Enterococci 95th percentiles) are:

Microbial Assessment Category (Enterococci 95th percentile - organisms per 100ml) Recreational Water Classification
0-200 Very good
201-500 Follow up
Greater than 500 Follow up

For each of the last five years the Recreational Water Classification has been 'very good' for all the beach and surf zone sites, because bathing and surfing water 95th percentiles have fallen into the '0-200' Microbial Assessment Categories.

Recreational Water Classification Results
(2000/01 to the end of the last financial year)
Swim and surf zone sampling sites
2000/01
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 41 VERY GOOD
2 2 VERY GOOD
3 2 VERY GOOD
4 2 VERY GOOD
5 84 VERY GOOD
6 6 VERY GOOD
Surf 800m
8 20 VERY GOOD
9 41 VERY GOOD
10 6 VERY GOOD
11 20 VERY GOOD
12 8 VERY GOOD
13 2 VERY GOOD
2001/02
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 2 VERY GOOD
2 0 VERY GOOD
3 0 VERY GOOD
4 0 VERY GOOD
5 12 VERY GOOD
6 3 VERY GOOD
Surf 800m
8 0 VERY GOOD
9 0 VERY GOOD
10 31 VERY GOOD
11 4 VERY GOOD
12 145 VERY GOOD
13 82 VERY GOOD
2002/03
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 5 VERY GOOD
2 0 VERY GOOD
3 2 VERY GOOD
4 0 VERY GOOD
5 8 VERY GOOD
6 5 VERY GOOD
Surf 800m
8 17 VERY GOOD
9 4 VERY GOOD
10 10 VERY GOOD
11 4 VERY GOOD
12 19 VERY GOOD
13 0 VERY GOOD
2003/04
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 27 VERY GOOD
2 4 VERY GOOD
3 2 VERY GOOD
4 2 VERY GOOD
5 2 VERY GOOD
6 2 VERY GOOD
Surf 800m
8 2 VERY GOOD
9 1 VERY GOOD
10 2 VERY GOOD
11 4 VERY GOOD
12 16 VERY GOOD
13 10 VERY GOOD
2004/05
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 2 VERY GOOD
2 0 VERY GOOD
3 2 VERY GOOD
4 2 VERY GOOD
5 17 VERY GOOD
6 3 VERY GOOD
Surf 400m
8X 165 VERY GOOD
9X 144 VERY GOOD
10X 45 VERY GOOD
11X 99 VERY GOOD
12X 192 VERY GOOD
13X 40 VERY GOOD
Surf 800m
8 2 VERY GOOD
9 1 VERY GOOD
10 6 VERY GOOD
11 8 VERY GOOD
12 7 VERY GOOD
13 3 VERY GOOD
2005/06
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 7 VERY GOOD
2 2 VERY GOOD
3 2 VERY GOOD
4 2 VERY GOOD
5 14 VERY GOOD
6 9 VERY GOOD
Surf 400m
8X 14 VERY GOOD
9X 22 VERY GOOD
10X 64 VERY GOOD
11X 77 VERY GOOD
12X 27 VERY GOOD
13X 44 VERY GOOD
Surf 800m
8 23 VERY GOOD
9 20 VERY GOOD
10 21 VERY GOOD
11 18 VERY GOOD
12 20 VERY GOOD
13 18 VERY GOOD
2006/07
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 10 VERY GOOD
2 0 VERY GOOD
3 11 VERY GOOD
4 120 VERY GOOD
5 62 VERY GOOD
6 18 VERY GOOD
Surf 400m
8X 74 VERY GOOD
9X 149 VERY GOOD
10X 70 VERY GOOD
11X 196 VERY GOOD
12X 17 VERY GOOD
13X 204 FOLLOW UP
Surf 800m
8 64 VERY GOOD
9 118 VERY GOOD
10 73 VERY GOOD
11 50 VERY GOOD
12 53 VERY GOOD
13 82 VERY GOOD
2007/08
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 22 VERY GOOD
2 28 VERY GOOD
3 2 VERY GOOD
4 13 VERY GOOD
5 18 VERY GOOD
6 11 VERY GOOD
Surf 400m
8X 26 VERY GOOD
9X 22 VERY GOOD
10X 10 VERY GOOD
11X 21 VERY GOOD
12X 14 VERY GOOD
13X 12 VERY GOOD
Surf 800m
8 22 VERY GOOD
9 18 VERY GOOD
10 20 VERY GOOD
11 18 VERY GOOD
12 12 VERY GOOD
13 19 VERY GOOD
2008/09
Site 95%ile Enterococci /100ml NHMRC Recreational Water Classification
Swim
1 482 FOLLOW UP
2 4 VERY GOOD
3 14 VERY GOOD
4 0 VERY GOOD
5 13 VERY GOOD
6 3 VERY GOOD
Surf 400m
8X 2 VERY GOOD
9X 2 VERY GOOD
10X 4 VERY GOOD
11X 2 VERY GOOD
12X 4 VERY GOOD
13X 2 VERY GOOD
Surf 800m
8 3 VERY GOOD
9 2 VERY GOOD
10 2 VERY GOOD
11 2 VERY GOOD
12 6 VERY GOOD
13 7 VERY GOOD

The raw data for this period is available here:
2008 / 2009 additional monitoring raw data (PDF, 62kb)

* There are many statistical methods for calculating the microbial risk category. To date MW has used the Excel Percentile method, however other methods are currently being investigated for use in future assessments.

Get involved

A Community Liaison Committee advises us on the Eastern Treatment Plant’s operations and assists with the development of the plant’s Environment Improvement Plan. Plant tours and open days are held regularly. Please contact Melbourne Water on 131 722.

Education Program

We have an extensive education program including curriculum materials and speakers program. We have experts such as environmental scientists and water recycling and treatment plant specialists who are available to speak to community groups and schools. Schools tours of the treatment plant and outfall can be organised. Please contact Melbourne Water on 131 722.

For more information

For more information on our environmental performance reporting, click on Melbourne Water’s 2006/07 Social and Environment Report.

South East Water’s monitoring program at its treatment plants at Mt Martha, Boneo and Somers includes monitoring incoming raw sewage, effluent sampling and chemical analysis. Visit their website for more information.