WaterBlitz results 2021

Thames, UK + Eindhoven, The Netherlands

24-27 September, 2021

Measurements collected by more than 460 volunteers in England and the Netherlands shine a light on the poor state of our rivers compared to European counterparts. Download the WaterBlitz report for key findings, results and analysis.

WaterBlitz Report


Led by Earthwatch Europe, the WaterBlitz is a four-day event designed to help investigate the water quality of specific areas over a short period of time. A total of 631 measurements were recorded in our latest pan-European WaterBlitz, bringing the global FreshWater Watch total to more than 30,000 datasets! Alongside our 12th event in the Thames catchment area, we were supported by Waterschap De Dommel and citizens from Eindhoven in the Netherlands.

Trouble in the Thames?

Our results show a dramatic contrast between the concentrations of nutrients (nitrates and phosphates) in the Thames compared to the River Dommel in Eindhoven. Over half of the water bodies that were tested across the Thames region this autumn showed higher-than-expected nutrient levels. By contrast, only one percent of Eindhoven water bodies were shown to have high concentrations of both nitrates and phosphates. An excess of these nutrients in water bodies is damaging for the environment, and can lead to algal blooms, deoxygenation of the water, and biodiversity loss. Certain types of algal bloom can produce toxins that are harmful to the health of humans, pets and livestock.

Nutrients commonly enter the water as a result of sewage pollution and runoff from agricultural land. On 20th October 2021, MPs rejected an amendment to the Environment Bill that called for a legal duty to be placed on water companies to reduce raw sewage discharges into rivers.

Dr. Izzy Bishop, Freshwater Research Lead at Earthwatch, said, “We have been running the Thames WaterBlitz for five years now and we see elevated nutrient concentrations across the entire region year-on-year. This is the first time we have also collected data from Eindhoven, and the differences are stark. The water industry in Eindhoven have been working hard to improve water quality across the city and it shows. This makes it even more disappointing for us to hear that MPs have rejected amendments to the Environment Bill that could have helped to clean up our waterways here in the UK.”

The data collected in Eindhoven will be used to ‘fill in the gaps’ in the monitoring system of the local waterboard “Waterschap De Dommel”, to maintain water quality and further improve water quality where needed. Students from the University of Utrecht will do a more extensive data analysis in coming months.

Ineke Barten, Senior Ecologist at Waterschap De Dommel said, “We were curious to see how our effort to improve water quality (remediate soil, improve riverbank conditions, create fish passages) paid off. The big advantage of a WaterBlitz is that volunteers go to many more waterways, including the ones we don’t regularly monitor like the city canals. It provides us with new information.”

Izzy adds, “Thanks to the efforts of hundreds of volunteer citizen scientists, we are collecting more data than ever before about the state of our water. Citizen science has a crucial role to play in environmental research, and is an accessible way for people to connect with nature and show how much they care about their local water environment. It’s vital that the government pay attention to the data they are collecting and act quickly to return our waterways to good health.”

An inspiring example of the importance of this data comes from the Evenlode Catchment Partnership (ECP) who are collectively delivering the Smarter Water Catchment project, sponsored by Thames Water. The focus of the project is to monitor and improve water quality in the River Evenlode. There is lots of good work being progressed under this project, but data collected by concerned local residents suggests that it could all be undone as sewage pollution from the water company itself is causing many of the problems observed in the river.

Evenlode River, Oxfordshire

The River Evenlode winds its way through some of the Cotswold’s most picturesque scenery and is a popular place for both residents and tourists to spend time beside. Children used to play in its ‘gin clear’ waters, and would watch the trout dashing through the water. These days, though, its pollution levels are so high that its waters are murky, and there is not a single place on the entire river that is designated as safe for bathing.

Read more

Download the WaterBlitz report for more insight and further analysis of the data collected. We have also partnered with the UK Centre for Ecology & Hydrology to publish an interactive map allowing the direct comparison between Thames WaterBlitz data and Environment Agency monitoring data. This map, along with relevant findings, will be shared with the Environment Agency, who will incorporate the research into their decision-making process. Click below to open the map.

Get Involved

There are many reasons to take part in a FreshWater Watch event. From wild swimming to farming, what motivates you?

I believe in protecting our rivers and see community engagement as an important part of scaling up data collection. Two values met in one bit of volunteering.

Community projects and scientific research have huge potential for making impact and positively influencing our health and well-being.

I swim in the Jubilee River so am concerned about the water quality both for swimmers and the wildlife that we share the water with.

I run a canoe club on the Thames and am interested in pollution levels and water quality.

As an angler I'm concerned about deteriorating water quality.

I am a secondary school science teacher. This is important work which I will be sharing with my classes and encouraging those old enough to take part in too.

We would like to understand the water quality in rivers and watercourses that flow through farmland we manage as we want to carry out environmental work to improve water quality.

Het leuke is vooral een steentje bij te dragen en te leren wat waterkwaliteit inhoudt. (The best thing is to do one’s bit, and to learn about water quality.)

Do you belong to a community group with an interest in freshwater monitoring? Click here to read about our Community Group subscriptions.

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Image credit: Peter White