The Wolvercote Mill Stream has been rated 'poor' for a third consecutive year, with the Environment Agency advising people to avoid swimming in it.

On December 1, the Environment Agency said there was the presence of harmful bacteria in the water.

This river, one of only two "designated bathing status" rivers in the UK, must achieve at least 'sufficient' status before 2027 to prevent its de-designation and the cessation of testing.

During the summer holidays, hundreds of people, including families, frequent the site to swim, paddle and frolic.

Harmful bacteria levels have remained significantly above safe limits from 2021 to 2023, despite significant variations depending on the weather.

Both the Environment Agency and Thames Water are inspecting the pollution source, with results due in early 2024.

Thames Water recently unveiled plans to improve upstream sewage treatment operations in Cassington, Church Hanborough, and Stanton Harcourt over the next five years.

Claire Robertson, Oxford Rivers Project Officer at Thames21, said: "It’s really disappointing to find out that the pollution on this stretch of the Thames hasn’t improved this past year.

"Investigations are all well and good, but only if they lead to action and improvements.

"We welcome Thames Water’s plans for upstream, but we would like to see them happen before 2027."

She added: “It’s such a shame that water-lovers in Oxford can’t enjoy a cooling summer dip without the fear of becoming unwell.

"It’s not the way it should be, as being on or in the water has so many benefits for our health and wellbeing.

"If you swim in the river, we recommend always washing your hands with clean water before eating food."

DEFRA has released the designations for 420 bathing waters across the nation, with most being beaches.

Richard Aylard, sustainability director at Thames Water, said: "We share the disappointment that Port Meadow bathing water is again likely to be assessed as ‘poor’ by the Environment Agency methodology despite the water quality for most of the season being satisfactory for bathing.

"However, we would advise waiting on the full results of the Environment Agency’s investigation into sources of bacteria into the river, before making any conclusions about the causes for the poor bathing water quality.

“There are multiple causes impacting the health of rivers.

"We’re working hard with the Environment Agency to understand the sources of bacteria in the river.

“Improving the health of rivers is a key focus for us and our draft business plan for the next five years includes UV disinfection at our sewage works in Cassington, Church Hanborough and Stanton Harcourt."