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Volunteers help reveal water pollution levels across Thames Valley and three European capital cities

Measurements collected by more than 1,100 volunteers across the Thames Valley and three European capital cities reveal the state of pollution in local rivers, streams, lakes and ponds, in a report published by environmental organisation Earthwatch Europe.

A total of 945 measurements were taken across the Thames Valley, Luxembourg, Dublin and Paris during the WaterBlitz which ran from 20 to 23 September, marking the first time that this event has occurred across Europe on the same weekend. Led by Earthwatch and funded by Thames Water, the WaterBlitz has taken place twice a year in the Thames Valley since 2015, with this year’s expansion into Europe being made possible by Earthwatch’s new partnership with Royal Bank of Canada (RBC).

Almost half of the measurements (432) taken in the European WaterBlitz this autumn were collected in the Thames Valley, which attracted a strong volunteer base of 276 people. The measurements provide a snapshot of local water quality which can then be compared to results from previous events to gain a better understanding of local waterbodies and the impact of conservation action in the area.

Pollution from nitrates and phosphates is a problem in the Thames catchment, where dense urban populations and intensive farming dominate the landscape. Data analysis from this latest WaterBlitz suggests that most waterbodies in the Thames catchment have medium to high concentrations of nitrate and phosphate nutrients – key indicators of agricultural and waste water pollution – with a few low measurements recorded between Oxford and London.

An excess of these nutrients in waterbodies can cause algae and certain species of plants to grow rapidly, outcompeting other plants for resources such as light, leading to a reduction in biodiversity. Algal blooms and their subsequent decay also reduce the amount of oxygen present in the water, which in extreme cases can lead to the suffocation of fish and invertebrates. In addition, certain types of algal bloom can produce toxins that are harmful to the health of humans, pets and livestock.

During this WaterBlitz, potential incidents of pollution were detected in the Thames Valley by volunteers. One such incident involved black water coming out of a pipe in Boundary Brook, a small tributary of the Thames in Oxford. This prompted a call-out to the Environment Agency, who then visited the site to investigate and rectify the problem.

Kes Scott-Somme, Aquatic Research Assistant at Earthwatch Europe, explains: “We are delighted with the level of participation in this first pan-European WaterBlitz. Thanks to the efforts of WaterBlitz volunteers, we have been able to measure water quality at hundreds of locations across Europe. This scale of research could never be achieved by scientists alone. The measurements taken across the four areas are invaluable in painting a picture of water quality in those areas.”

In addition to monitoring nutrient levels, volunteers also recorded litter, which was found at 14% of sites in the Thames Valley. Litter in ponds, lakes, rivers, and wetlands is not only detrimental to animals using the water, but can also easily find its way to the ocean, where it can remain for hundreds of years.

“This is a fantastic example of the power of citizen science and of how we can all do a little something to learn more about – and ultimately take action to tackle – the sources of pollution in our precious water environments,” says Claudia Innes, Environmental Projects Executive, Thames Water.

Earthwatch will be working with Wild Oxfordshire, the Evenlode Catchment Partnership and Thames Water to make the data collected across the Thames Valley openly available on the FreshWater Links platform. Access to this data will enable key stakeholders – including water managers and local authorities – to access up-to-date information and make more informed recommendations for the improved management and health of our waterbodies.

Scott-Somme adds: “Much work has been done to reduce nutrient concentrations throughout the Thames in recent years, but while progress is being made, it is clear that efforts need to be increased to ensure the improvement of water quality in the area.”

View the full results, including those for Dublin, Luxembourg and Paris, here.


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