More than half of Scotland wild swimming spots have unsafe levels of sewage
Analysis by investigative journalism platform The Ferret found that since the start of May more than half of the wild swimming spots breached European safety limits for faecal bacterial at least once when tested.
The highest levels were found at Lower Largo beach in Fife, where levels were at least 50 times the safe limit on three occasions, according to the figures.
Freshwater bathing spots at Luss Bay, on the banks of Loch Lomond, and Dores beach, near Loch Ness, also returned very high levels.
The contamination is typically caused by heavy rain which leads to sewers to overflow or washes animal faeces from farms into the waters.
The investigation of the 89 water spots was undertaken by Sepa between five and 18 occasions between May and September 15.
The sampling checks waters for concentrations of E.coli and intestinal enterococci (IE) which are found in faeces.
European standards require bathing waters to be rated either excellent, good, sufficient or poor.
Any coastal water rated poor - or fewer than 500 colony-forming units (CFU) for E-coli and fewer than 185 CFU for IE - must advise against swimming.
It covered designated spots, where the areas are considered to have more than 150 visitors.
Scottish Water have said not all cases of contamination are linked with discharges from sewers and said it assess levels regularly.
Mr Cole-Hamilton said: "This shows the SNP and Greens are letting the Government-owned water company off the hook for dumping sewage into our rivers, lakes and beaches.
"It's time ministers stopped excusing these filthy practices when levels of faecal bacteria on our own beaches are reaching 50 times the safe limit. No wonder people are thinking twice before dipping their toes in.
"Scottish Liberal Democrats are leading the calls for all sewage discharges to be recorded and published to uncover the true scale of the problem, legally binding targets to tackle sewage dumping and measures to upgrade Scotland's Victorian sewage systems. It's time to end the sewage scandal."
A Scottish Water spokesperson said: "Not every case of high levels of contamination at a bathing water is associated with Scottish Water discharges because some bathing waters have no Scottish Water discharges nearby. Agricultural run-off can often a significant factor.
"Scottish Water ensures its assets are performing properly before and during the bathing season.
"Whenever there is a high result, meeting the agreed trigger level, we carry out investigations to ensure our assets are operating as intended."
Scottish Water is also assessing how to mitigate the impacts at Lower Largo and £2.7 billion has been invested in improving the public drainage system across the country in the last decade.
The spokesperson added: "We check our assets' performance before and during the bathing season and carry out any remedial action required. We also review asset performance after any high result that meets agreed trigger levels.
"Scottish Water is committed to continuing to support the protection and improvement of rivers, coastal waters and beaches and we were pleased to hear from Sepa this summer that there are more bathing waters than ever before and a record number were rated excellent."
The Scottish Government has been approached for comment.
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