Blackmans Bay Water Quality

No, the beach is not closed.

Council cannot stop the public from accessing or using the beach. However, we do not currently recommend swimming in the southern section of the beach due to the new long-term “Poor” water quality rating.

This area will be clearly signposted to make members of the public aware of the impacted area.

Enterococci is the indicator used in the summer monitoring program.

Enterococci levels in these samples are measured in cfu/100ml (colony forming units per 100mls).

Enterococci is a faecal bacterium that is indicative of the presence of sewerage but can also be present from other natural sources in the environment such as agricultural runoff, birds and animals.

Water contamination by sewage and animal faeces may pose a health hazard when the water is used for primary contact recreation, such as swimming.

No. The beach rating is based on a long-term grading system.

The long-term rating is not a representation of what the water quality is like from one day or one week to the next. The rating is based on the last five (5) years of sampling data.

This doesn’t mean the water quality is poor every day at the south end of the beach, as test results show that 81.5% of our samples over the last 5 years have passed.

When a monitoring site at a recreational beach records five (5) results over the trigger level, then that beach shall be given the rating associated with the below:

Five (5) results in five years that are above 280 = “Fair” rating.

Five (5) results in five years that are above 500 = “Poor” rating.

The southern section of the beach has been classified with a “Poor” grading, as there has been 6 results out of 87  that exceeded the threshold (500 cfu/100ml); over the last 5 years.

Following every summer swimming season, the sample results are added to previous results, and the results from five years of sampling are collectively used to calculate a new long-term rating by the Derwent Estuary Program.

It is unlikely that you will become sick.

As always, if you are concerned, we would encourage you to talk to your GP or other healthcare professional.

The trigger levels for enterococci are set by the National Health and Medical Research Council and are based on the amount of ingestible portions that a swimmer is likely to consume on an annual basis.

Regular swimmers will have a greater exposure and are assumed to ingest a larger amount of water annually.

Council is continuing to investigate why Blackmans Bay south’s water quality is impacted by contamination from time to time whereas the middle and North sites are not. Investigations undertaken to date have not been able to identify any clear correlation between possible contamination sources and water quality at the southern end of Blackmans Bay.

While we cannot point to the exact cause of the high results recorded at the southern end of Blackmans Bay Beach we do know that there are 3 stormwater outlets in the area. Standard public health advice is to not swim close to stormwater outfalls and after heavy rain.

Council is looking into options in partnership with TasWater to reduce the contamination inputs into the stormwater that drains to this location. This is not a quick solution and requires extensive investigations and research to develop a staged plan moving forward.

Council has a dedicated Stormwater Investigations Officer who undertakes weekly sampling to track and trace potential sources of contamination.

Council is currently examining the stormwater network in the Blackmans Bay area including in particular the network which drains out in the southern end of Blackmans Bay Beach.

Council will also continue to work with our partners – the Derwent Estuary Program and TasWater, to track and trace the source of any potential bacteria issues and assess existing sewer and stormwater infrastructure in the community as well as investigate any additional scientific monitoring programs moving forward.

Highly unlikely. Previous investigation into seagull numbers and water quality found no clear links between the seabirds and the contamination in the area.

While it’s difficult to absolutely and conclusively rule out that the sea birds are a contributing factor, as enterococci is known to be present in bird faeces, there have been periods of extremely high seagull numbers on the beach and simultaneously very good water quality samples results.  There are also times when there is very poor water quality at a time when there are very few, or no seagulls at all.

Council could extend the stormwater pipes further out into the Derwent River though this would be a multimillion dollar project which would require either Federal or State funding or be spread over many years of Kingborough Council Capital funding. There is no conclusive evidence that this would solve the issue.

Be aware that anything that you put into the stormwater network will wash out at the beach.  Whatever gets washed down the drains on all our streets ends up in our waterways and beaches.  Report water leaks and sewer spills to TasWater. In dry weather if you see water flowing over roads and walkways please report to TasWater on 136 992 as soon as possible.  

Keeping our community updated is an important priority for Council and that is why we have dedicated part of our website to hosting our current test results and locating information for the public on stormwater across the community. 

Council will also regularly update its social media channel and website with any further developments and continue to work with the local community in keeping them informed of future developments. 

Blackmans Bay Beach Water Quality Winter Testing