People are being urged not to swim in the sea at one Kent beach, however tempting taking a dip might be during this weekend’s heatwave.

The Environment Agency says the warning for St Mary’s Bay, in Romney Marsh, is likely to stay all summer because of poor water quality.

The words of caution come as temperatures in some parts of Kent are this weekend expected to rocket to a stifling 30C, which will lure more people towards the coast.

A spokesman for the Environment Agency (EA) told KentOnline yesterday: “We continue to work with our partners to fully investigate the reasons for the decline in bathing water quality at St Mary’s Bay.

“The poor classification means that we are advising against bathing at St Mary’s Bay and the local authority has erected signage to reflect this at the site.

“Our advice against bathing is advisory and public access to the beach and the bathing water remains open.”

A year-long warning was announced in February after the discovery of unsafe levels of bacteria in the water.

Monitoring by the Environment Agency had revealed heightened traces of intestinal enterococci, found in faecal matter.

The EA said it was working with other agencies to find out what caused the spike in bacteria in the area, which is popular with tourists during the summer.

Cllr Tony Cooper, who represents the Romney Marsh ward on Folkestone and Hythe District Council, said: “People were concerned the adverse publicity would affect visitor numbers – however, that happily wasn`t the case.

“Visitor numbers have not dropped and the businesses in Dymchurch and St Mary`s Bay are looking forward to welcoming visitors and for families to be enjoying donkey rides and ice cream on the beach.”

A spokesman for St Mary in the Marsh Parish Council added: “It is impossible to identify if there has been early signs of a fall in visitors due to the quality of bathing water.

“The strong north easterly winds have made the coastline so cold for several weeks, will have been off putting to visitors.

“The water is tested regularly, and whilst the EA has advised not to swim, for twelve months, there is no ban and the last test identified the water quality as good.”

The EA monitors water quality between May and September by taking samples at designated bathing sites.

St Mary’s Bay is the only site in Kent where a "do not swim" warning is in force.

To find out what caused the problem, the EA is monitoring potential sources of pollution such as septic tanks.

Samples will continue to be taken at St Mary's Bay during the summer and, if improvement is eventually found, the overall classification of the water quality could be upgraded at the end of the bathing season.

The water quality at St Mary’s was classed as poor in 2022 after being rated “sufficient" in 2019 and 2021, and “good” in 2018.

The nearest bathing spots along the coast, at Littlestone and Dymchurch, both have a "good" rating at present.

It comes as water company bosses have come in for criticism for dumping sewage into the sea in other parts of Kent.

Fed-up traders in Herne Bay blasted Southern Water for releasing wastewater into a bathing area during a dry weekend last month.

The first heat health alert of the year for Kent is from 9am on Friday to 9am on Monday and also tells of temperatures going well above average at night.

The yellow warning, which is expected to be nationwide, was issued by the UK Health Security Agency and the Met Office.