Water quality testing with River Action at Henley
28th June 2024
Earthwatch helped campaign group, River Action, to analyse data collected by citizen scientists at sites around Henley on the River Thames. The testing, ahead of the Henley Regatta, revealed high levels of nutrient pollution and worrying levels of microbial pollution from some test sites.
Executive summary
This River Action report analyses water quality data collected at multiple sites around Henley on the River Thames. The report includes analysis of nitrate and phosphate concentrations collected throughout 2023 to June 2024 and Echerichia coli (E. coli) measurements taken in late May and June 2024.
Looking at all the samples collected throughout the year, the highest levels of phosphate and nitrate were in the summer, followed by spring. These levels were well above recommended limits, especially for phosphate. Phosphate and nitrate levels were lower in the autumn and winter, but nitrate still exceeded recommendations. Higher summer turbidity (cloudiness) might be linked to algae blooms.
Algal blooms can harm aquatic plants and wildlife by blocking sunlight needed by plants, and using up oxygen, suffocating fish.
The report didn’t find any clear increase or decrease in E. coli levels in June. However, it did find very high levels of E. coli in one sample from Fawley Meadows in June. This could be an error, but it suggests the water quality there may be unsafe.
Overall, the water quality seems to be worst in the Upper Thames and Temple Island areas, with very high phosphate and nitrate levels. Monitoring should continue, and sources of nutrient pollution should be investigated, especially for these two areas.
Great UK WaterBlitz
The findings of the River Action Henley report align with the analysis conducted for Earthwatch’s Great UK WaterBlitz, the UK’s largest citizen science water quality monitoring event. The WaterBlitz, which took place over the weekend of 7-10 June, saw over 2,600 people across the UK measure the nutrient pollution in their local rivers, streams and lakes.
You can explore the results further in the Great UK WaterBlitz June 2024 report: