AN investigation is under way and swimmers were urged to avoid Grève de Lecq after high levels of E.coli were found in the water.
Routine testing – which began this week at the start of a five-month “monitoring season” – revealed concerning concentrations of the bacteria, which can cause serious illness.
Warning signs have been erected at slipways and steps leading to the beach.
Director of public health Peter Bradley said the investigation by the pollution control team was continuing, but that the cause of the poor water quality was not yet known.
“Environmental Health staff have been sampling and will keep monitoring levels, as well as looking into the primary cause,” he said.
“There’s every reason to believe this is an isolated incident, but we do monitor other bays.”
The reading from the sample taken earlier this week was 3,300 parts E.coli per 100ml, compared with the threshold of 500 where “good” water quality becomes “poor”.
Professor Bradley said the effects of E.coli infection could potentially be serious, but were normally “quite mild”.
Typical symptoms include diarrhoea, with blood present in around half of cases, as well as the possibility of vomiting and a fever.
Although some sea swimmers have called for water quality to be monitored throughout the year, the current programme encompasses only the summer months, starting this year on 13 May and continuing on a weekly basis until 24 September.
Concerns about water quality levels were raised last summer, when a problem at the Bellozanne sewage plant led under-treated sewage to flow into St Aubin’s Bay in June.
Islanders were advised not to swim in the sea between St Helier and Belcroute for three days, with government officials stating at the time that the issue at Bellozanne was caused by warm weather and a lack of rain, as well as insufficient “organic matter” flowing through the plant for the bacteria used in its chemical processes to function properly.
A regulation team has been formally investigating what happened last June under the Water Pollution (Jersey) Law 2000, with the possibility of fines for breaches.
The investigation into the June 2023 incident has yet to be concluded. The JEP has asked for an update about what progress has been made.
Water quality for rivers and coastal areas of the UK has become a significant issue in recent years, with a number of pollution incidents, most recently at Windermere in the Lake District earlier this week.
Water campaigner and former Undertones singer Feargal Sharkey has been among the fiercest critics of water companies and the UK government, highlighting what he described as “the decaying state of our rivers”.
He said water companies were responsible for record sewage discharges into England’s waterways last year, with recent data showing that raw sewage was discharged into rivers and seas for more than 3.6 million hours, more than double that in the previous 12 months.
