Wolvercote Mill Stream designated as poor for third year running, but improvements on the way

Wolvercote Mill Stream at Port Meadow, one of only two “designated bathing status” rivers in the UK, has been rated “Poor” and advice against swimming in this stretch of the River Thames has been given by the Environment Agency for the third year running.

Water quality testing carried out by citizen scientists and Thames Water in 2021 [1], and the Environment Agency in 2022 and 2023 [2] have all found that harmful bacteria at the site are present above safe levels, although the levels vary significantly depending on the weather.

Hundreds of people, including many families, use the site, especially in the summer holidays, to swim, paddle and play [3].

The Environment Agency and Thames Water are both carrying out investigations into the source of pollution at the site, with results due in early 2024. The law states that the site must achieve at least “Sufficient” status before 2027, otherwise it could be “de-designated”, and the testing stopped.

Thames Water has recently released its plans to improve sewage treatment works upstream of Wolvercote (Cassington, Church Hanborough and Stanton Harcourt) over the next five years[4].

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.”

“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.

“We as local people can also do something about this. Check the pipes in your house are connected correctly (for example, the wastewater pipe from a toilet or dishwasher should never be connected to a rainwater pipe). Contact Thames Water and your local representatives and ask them to prioritise these improvements.”

The results come from DEFRA as they release the designations for 420 bathing waters across the country, the vast majority of which are 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. Pollutants, animal faeces from livestock and wildlife, along with run off from farms and roads can contribute to hazards found in watercourses. 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. This is in addition to an upgrade that was recently completed at Stanton Harcourt and further work which will start at Church Hanborough in August 2024. We’re also currently designing plans to upgrade Cassington, which is due to complete in 2025.” 

  1. Oxford Rivers Project Citizen Science final water quality report, May 2022 https://endsewagepollutionthames.wordpress.com/water-quality-testing/
  2. Environment Agency: Water samples history, Wolvercote Mill Stream https://environment.data.gov.uk/bwq/profiles/data-samples.html?site=ukj1402-11946
  3. Application for designation as a bathing water (Wolvercote Mill Stream, February 2022) https://consult.defra.gov.uk/water/consultation-on-designation-of-wolvercote-mill-str/supporting_documents/wolvercotemillstreambathingwaterconsultation.pdf
  4. Thames Water PR24 Our Business Plan 2025-2030 https://www.thameswater.co.uk/media-library/home/about-us/regulation/our-five-year-plan/pr24-2023/our-business-plan.pdf
  5. Defra’s bathing water quality results 2023: https://www.gov.uk/government/statistical-data-sets/env17-bathing-water-quality-additional-datasets