River Cherwell is 'not healthy' - Banbury area volunteers test water over a year with worrying results

The group of volunteer ‘citizen scientists’ from Banbury and the surrounding villages completed over 180 water samples in the past year as part of a project to fight back against pollution in the River Cherwell and its tributaries.

And the sad result is that the River Cherwell is not healthy. Along its entire length from its headwaters in Charwelton to where it joins the Thames at Oxford not a single section is classed as ‘in good ecological health’ by the Environment Agency.

Rivers can be polluted by wastewater (sewage), run-off from farmers’ fields, and run-off of chemicals from roads and towns.

Banbury water volunteers (from Banbury Community Action Group, Wild Banbury and the WI) have been on a mission to find out why the Cherwell is failing its health checks.

Every month, they have tested for levels of phosphates and nitrates in their local river or stream. Phosphates and nitrates are nutrients that can cause algal blooms which starve the river of oxygen.

The project started in March 2023. Now, a year later, they have completed 187 samples from Fenny Compton in the north to Adderbury in the south. Of these samples, 86 per cent have high levels of nitrate but only 13 per cent have high levels of phosphate.

Claire Robertson, from Thames21 and the Cherwell & Ray Catchment Partnership, is helping to co-ordinate the sampling.

“I’m so pleased and impressed with how enthusiastically the volunteers have taken to the sampling” she said. “These samples are filling in crucial information about not only where and when river is polluted but also what is causing this.

"The elevated levels of nitrate we are seeing, compared to phosphate, indicate that run-off from agriculture is probably a bigger problem in this area than sewage pollution.”

Sue Smith, Climate Ambassador for Cropredy WI explained why she felt motivated to take part in the project.

“Testing the water of the River Cherwell at Cropredy once a month is a very practical way to act on our WI resolution 2023, Clean Rivers for People and Wildlife,” she said.

"By water testing, we can engage with our community, the water companies and government to make a real difference to the quality of our waterways over a sustained period.”

There are plenty of ways for new volunteers to get involved with protecting local waterways.

On April 18 there is a training event at Waitrose Community Room in Banbury, which teaches people how to look for and record drains polluting rivers. Anyone is welcome to join the mailing list to hear about more events and opportunities to take part - just email [email protected] for more details.

If local farmers would like to have a free farm visit for advice and funding opportunities for more efficient nutrient management and farming for water, they can get in touch with the Catchment Sensitive Farming team at [email protected]

• Only 15 per cent of rivers in England, and 6 per cent in the Thames basin are classed as ecologically healthy . For a map of the Cherwell basin and the streams which are healthy/unhealthy, follow this link: storymaps.arcgis.com/collections/e7421d95229843d7a34a3c25f8f4e7de?item=3