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Update: Sample analysis of Portobello Central bathing water sample not definitive for source

Date published: 24 July 2024

Bathing waters

Results of further analysis done on a water sample taken at Portobello Central has been unable to identify the source of the high bacteria count that resulted in SEPA advising against bathing near the start of July.

Microbial source tracking (MST) uses DNA-based techniques to determine the sources of bacteria in water. Knowing whether the source is ruminant (cows, sheep etc), dog, gull or human can help to identify sources of water pollution to allow for better understanding of impacts. At Portobello, long-term sampling and MST analysis has shown that the three main sources of pollution tend to be human, dog and gull. 
 
Due to the recent high bacteria count SEPA officers checked Scottish Water assets in the area, as well as other potential sources, but no signs of pollution were detected. If the high result had been caused by sewage a clear MST indication of human would be expected.
 
Signage was changed on Wednesday, 10th July to advise against bathing as a precautionary measure.  Another sample was taken on Thursday 11th July and advice against bathing was removed on Friday 12th July when analysis showed water quality was back to normal.
 
Vicki White, SEPA Senior Manager in Environmental Performance, said:
 
“The fact that a follow-up sample taken on Thursday 11th July showed water quality was already back to normal indicates this was a short-lived event that had no lasting impact. 
 
“Microbial source tracking can be very helpful in identifying a source, but in this case our analysis of this one sample has not been able to identify one. However, these results - combined with the fact our officers found no issues when we checked Scottish Water assets in the area - does indicate that this was not a sewage related incident.
 
“While this single result cannot give us a definite answer, it is a good reminder to clear up litter, as food sources can cause gulls to gather in large numbers. Picking up after your dog is another simple things people can do to help protect water quality – and make a beach visit more pleasant for other visitors. 
 
“Water sampling will be ongoing throughout the bathing season as part of routine testing, and we will continue to investigate any high bacterial results and take actions to tackle any pollution sources identified.”

Notes to Editor