The bathing water quality of three island beaches has been rated as ‘excellent’.
But four beaches have failed to reach even the minimum standard.
The island has eight designated bathing waters under Europe’s highest water quality standards.
Of these, three - North Ramsey, Glen Wyllin and Port Erin - have seen their end of season classification increase from ‘good’ to ‘excellent’.
Bay ny Carrickey, Douglas Central, South Ramsey and Port St Mary have all been rated ‘good’ in the latest bathing water report, just as they were in 2022, and Castletown beach is once again classed as ‘sufficient’.
Of the non-designated bathing waters, four - Douglas Summerhill, Peel, Fenella beach and Laxey - do not meet the minimum ‘sufficient’ standard.
This is an improvement on 2022, however, when no fewer than seven were classed as ‘poor’.
But three rated ‘good’ - Douglas Broadway, Port Lewaigue and Port Soderick - and Derbyhaven, which has been classified as ‘excellent’, could seek designation in future as bathing waters.
The Environmental Protection Unit carries out bathing water sampling during the bathing season over a 20-week period from May 1 to September 18.
Samples are analysed for faecal indicator organisms.
Local authorities were first invited to apply for a location to be designated as a bathing water in 2021.
Three new designated bathing waters were approved for the 2023 bathing season - Glen Wyllin, North Ramsey and Bay ny Carrickey.
Port Erin had been rated as ‘excellent’ in 2021 but its rating fell to ‘good’ in 2022. It has gone back up to ‘excellent’ in the latest results.
The report says 95% of Escherichia coli (EC) and 90% Intestinal Enterococci (IC) results there achieved ‘excellent’ or ‘good’ classification.
It notes that heavy rain on September 10 and 11 is likely to have caused elevated bacteria due to agricultural run-off into the Port Erin stream which discharges onto the beach.
The report says that overall, the 2023 bathing water samples were better than 2019, 2020 and 2022 with only 2% of EC and 8% of IE samples being classified as ‘poor’.
‘The improvement in the number of samples achieving excellent classification during 2023 is likely to be due to the dry weather in May and June,’ it says. ‘July was recorded as the wettest on record and August was similar to the long-term average.’
No applications were received from any local authorities requesting designation of any new bathing waters for the 2024 season.
Millions of litres of untreated sewage continues to be pumped into Peel and Laxey bays.
Earlier this month, Manx Utilities announced that its plans for sewage treatment in Peel and Laxey had been delayed by a year.
The new Peel treatment works had been due to be completed by the final quarter of next year.
But issues with supply of vital wastewater treatment equipment have delayed the target for full commissioning to the final quarter of 2026.
However, Manx Utilities says elements of the project can be completed earlier to provide clean bathing water by the summer of that year.