A do-not-swim warning will be enforced at one of Kent’s busiest beaches in a “terrible” blow to businesses at the tourist hotspot.

The water quality at Dymchurch beach on Romney Marsh has been downgraded to “poor” following investigations by the Environment Agency.

Meanwhile, a section of the shoreline in Deal has also been given the worst-possible rating.

Both sites were rated “sufficient” last year - but increasing levels of bacteria such as E. Coli have resulted in the new rankings.

Folkestone & Hythe District Council (FHDC) leader Cllr Jim Martin (Green) told KentOnline “no-swim notices have to go up” until a new ranking for Dymchurch is released next year.

He said: “It’s terrible - it cannot be underestimated.

“We have got a trajectory here that is downwards – Sunny Sands only escaped by the skin of its teeth in Folkestone. ‘Sufficient’ for Sunny Sands? Just do me a favour.”

Elsewhere on Romney Marsh, Littlestone beach has kept its “poor” grading, meaning its do-not-swim warning will remain.

However, just along the coast at St Mary’s Bay, the ranking has been upgraded to “sufficient”.

This means the beach can finally lift its advice against swimming in the sea, which has been in place for almost two years.

Elsewhere in the district, Sandgate and Hythe’s beaches have been rated as ‘excellent’.

Cllr Martin added: “Southern Water are the polluter and the Environment Agency is our guardian. It seems to me that something’s gone terribly wrong here somewhere because the pollution is going up.”

Southern Water said earlier this year the issues at Littlestone and St Mary’s Bay are not associated with its storm overflows.

The Environment Agency said in April that there is “no single cause” and it has identified a number of sources, including dog and bird faeces and people misconnecting toilets and showers.

Cllr Stephen Scoffham, cabinet member for environment at FHDC, says he is “extremely worried” about the downgrading of Dymchurch - a sandy beach packed with sunseekers in the summer months.

“This is bad for local people, bad for tourism and business and bad for the environment,” he said.

“We have been pressing the Environment Agency to get to the root of the problem and to use their enforcement powers where needed.

“Beaches across the region have been downgraded over the past few years. This is quite unacceptable.”

Cleo and Chimene Proctor, who run Sundaes ice cream parlour in Dymchurch high street, previously said a do-not-swim warning would mean holidaymakers “would go elsewhere”.

“During the summer period, our main clientele is holidaymakers coming to the beach,” Chimene said.

“It won't just affect us. So many of the businesses here rely on people visiting the beach.

“We do have some regular customers who live locally, but we really do rely on the tourists visiting the village.”

The Environment Agency’s monitoring of designated bathing waters during the official swimming season between May and September reveals 8.2% of bathing waters in the country – some 37 sites – were rated “poor” for water quality in 2024.

The proportion of sites failing to meet minimum standards in water quality and being rated as poor as a result has nearly doubled from 4.3% last year, and is the highest since the current rating system was introduced in 2015, while the percentage of “good” and “excellent” sites has fallen slightly.

The bathing water season runs from May to September every year, and the Environment Agency takes samples measuring E. Coli and other pollution over that period.

Herne Bay Central and West Bay in Westgate have also been rated “sufficient”. All the other beaches in Kent have rankings of “good” or “excellent”.

KentOnline previously reported how residents fear the downgrading of Deal Castle Beach would “kill” their coastal town.

It comes seven years after Southern Water announced Deal would enjoy a £3.9m investment as part of its ‘Magnificent Seven’ scheme.

A spokesperson for Southern Water said: “We have published our annual bathing water report which sets out what we are doing to protect and enhance these precious coastal environments.

“This publication responds directly to today’s Environment Agency announcement of 2024’s bathing water classifications, which ranks 84% of our 87 designated bathing waters as ‘good’ or ‘excellent’.

“Southern Water has an important part to play in improving and maintaining water quality, but there are many other factors that impact it - agricultural, highways and industrial runoff, as well as the impact of animals and marine activity.

“Partnership working is vital and we’re delighted that so many councils and organisations are working with us and together to bring the outcomes we all want.”

Environment Agency chair Alan Lovell said: “Bathing waters are hugely important for communities and for the environment – and we know there is growing public demand for bathing sites across the country, including at our lakes and rivers.

“While overall bathing water quality has improved in recent decades due to targeted investment and robust regulation, today’s results show there is much work still to do, particularly to bring our inland bathing waters up to standard.

“We are working with the water industry, farmers and local authorities and are investing in our regulation, with more people on the ground, updated digital assets and new legal powers to improve our bathing waters for all.