FreshWater Watch Champions: Dave Wallace and the Henley River Action Group - Earthwatch

FreshWater Watch Champions: Dave Wallace and the Henley River Action Group

A blog written by Henley-based citizen scientist, Dave Wallace, who decided to take action against river pollution with support from River Action UK, Windrush Against Sewage Pollution and our FreshWater Watch programme.

Freshwater pollution – the time to act is now!

This article is written against a backdrop of increasing anger about the dire state of the UK’s water industry and how lack of investment has polluted our rivers and seas. Just 14% of the UK’s rivers are in good health. The abuse of our waterways can only damage us all in the long run. Water is a precious resource. It is a story of action and the positive contribution of citizen science

Why water matters – a personal story

I grew up in the water, having lived my early days in Kenya and Fiji. When I was a teenager, my brother gave me a book to read; Waterlog by Roger Deakin. It was a diary of his wild swims all over the British Isles. It captivated me and left a lasting impression. One day in my 40’s, I found myself donning a wetsuit and, along with friends, jumping into a lake to swim. The sensation of cold and energy acted like medicine to my brain. I felt immediately soothed; I felt at home. From that moment, every time I went past a body of water, I would assess its swim worthiness, which soon led me to swim in the Thames. 

The River Thames in Henley  

The Thames is a majestic and powerful force of nature. As one of the most recognisable and known rivers globally, its history is the history of England and the UK. London is a world capital built around and because of it. I feel connected to that history every time I swim in the river. I live in Henley. The River Thames is stunning here, both upstream towards Shiplake and Sonning and downstream towards Hurley and Marlow. There is also the Henley Mile, which provides a stretch of river that is straight enough and wide to be ideal for rowing races. It is the course of the Henley Regatta, one of the world’s oldest and most renowned rowing regattas. 

Henley Regatta 2023. Image credit: River Action UK & Maureen McLean Photography

Swimming in sewage

It is also the site of the Henley to Marlow marathon, a 14km swim every August, which I had wanted to swim in 2022. Race day was at the tail end of the drought that hit the UK in the summer of 2022. It hadn’t rained for weeks. However, the water quality was not great and seemed to get progressively worse, and by the time I arrived in Marlow, I was swimming in what appeared to be raw sewage. A fellow swimmer got ill. I posted on LinkedIn about my achievement and mentioned the faecal water I had encountered. This led to a connection with River Action, a charity focused on highlighting and addressing the pollution problems our rivers face in the UK, and Windrush Against Sewage Pollution (WASP).

Water testing as a way to take action

It was decided that we would do testing on the Henley Mile for a whole month. It would be the most intensive testing on a single stretch of river that had ever been undertaken. River Action paid for the kit we needed and the lab analysis that would be undertaken to check for levels of E Coli and Enterococci. Additionally, Soraya Wooller from Earthwatch Europe’s FreshWater Watch programme provided test kits and training so we could test for nitrates, phosphates and water turbidity (how clear the water is). Earthwatch’s kits delivered readings within minutes, which could be uploaded to an app (along with observations) from the river bank. Two test sites were selected for us, and with the training over, we, the Henley River Action Group, started. 

FreshWater Watch water testing chart reveals high levels of nitrates. Image credit: River Action UK & Maureen McLean Photography

The test results

What we found was depressing. 

  • The E-coli and intestinal enterococci test results showed a significant deterioration in water quality after a rainfall event, taking the overall status at both test locations from ‘good’ to ‘poor’.
  • Levels of e-coli were four times higher than had been recorded in the sampling from the start of the testing period. The levels recorded meant that the water in Henley would have posed a significant health risk to all water users, especially swimmers.
  • Phosphate and nitrate testing results indicate that the River Thames at Henley is excessively nutrient enriched and in a very poor ecological condition. 
  • 34 out of 40 phosphate results recorded were 0.2 mg/l or above. 37 of the 40 nitrate samples measured levels of 2 mg/l or above. Any phosphate reading of 0.1 mg/l or above or nitrate reading of 1 mg/l or above is considered ecologically damaging for rivers.

The results of our testing are being shared widely in the local and national news. River Action and Earthwatch are using this evidence to raise awareness and hold Thames Water to account. It feels good to know that the work of our small band of citizen scientists has had such an incredible impact. 

A more respectful treatment of our waterways

The other outcome was that we connected more deeply with the river. By visiting and studying it daily, we got to know it intimately. We saw this magnificent river endeavouring to do its best. Despite its ill health, it was still a home, a nursery, a refuge. A larder. A place of enjoyment, solace and reflection. The testing has opened my eyes to its struggle. It is sick, and we have the evidence to prove that fact. We are treating this mighty river with contempt. It is abused, and to what end? Without the river, Henley is nothing. We are nothing. 

We have to start treating our waterways with the respect they deserve. Solving the problem will require policy changes and innovative technologies, but the power of community-based initiatives should not be underestimated. 

Testing continues!


The results of Dave’s water testing activities, carried out with his group during the Henley Regatta 2023, have been featured in major news outlets including The Guardian and BBC News. His campaign also got support from British wildlife presenter and naturalist, Steve Backshall.

This blog has been edited. Read the full version on LinkedIn.

Find out more about our FreshWater Watch programme. Funding opportunities are currently available for new water monitoring groups in the UK! 

Website by AgencyForGood

Copyright 2024. All Rights Reserved

Skip to content