High levels of pollution found in river Frome
A SURVEY by "citizen scientists" to test the health of the river Frome found high levels of pollution in more than half of samples.
Charity the Bristol Avon Rivers Trust recruited 193 volunteers to take part in water quality testing in local streams and rivers across the Bristol Avon Catchment in its WaterBlitz event, held during one week in July.
They were given sample kits and asked to make visual observations of the colour of the water and the presence of oil or litter.
Their results, which have now been analysed and published, show levels of pollution on the rise.
A total of 47 samples were taken from the river Frome – which flows through Frampton Cotterell and Winterbourne Down on its way from its source at Dodington to Bristol's Floating Harbour – along with its tributaries.
Of these, 53% of samples showed a high level of nutrient pollution while 34% showed a medium level.
High levels of polluting nitrates and phosphates were recorded at locations including the Frome Valley Walkway near Rockwell Wood at Kendleshire, Huckford Quarry, and Damson Bridge and Bury Hill Bridge, Winterbourne Down.
Medium levels of nutrients were recorded at several other locations, including at Black Rocks, Frampton Cotterell.
Bristol Avon Rivers Trust project manager George Clark said: "Nutrient pollution level is the combined impact of phosphates and nitrates in the watercourse.
"Nutrients, particularly phosphates and nitrates, are amongst the most common pollutants of freshwater across the world. As a result of their wide-ranging effects, levels of phosphate and nitrate are widely used as indicators of water quality."
He said that the results showed a "significant increase" in the proportion of samples showing high nutrient pollution from around 1 in 5 last year to more than half 12 months later.
High nutrient levels can affect wildlife and cause a decline in water quality, making it less safe, because they encourage plant growth, in particular algae which uses up the oxygen in the river and blocks out light.
George said that the causes of high nutrient levels included: agricultural pollution, caused when livestock are kept near a river or fertilisers are washed off the land; garden pesticides and fertilisers washed into our rivers, especially through the drainage network; combined sewer overflows (CSOs) used to provide relief to the sewer system and prevent homes from flooding during periods of heavy rain.
He said: "Unfortunately, when CSOs kick in, rainwater mixed with raw sewage, containing nutrients such as phosphate and nitrate, is discharged into our rivers."
The project was funded by bodies including Bristol Water, Wiltshire Wildlife Trust and the People’s Postcode Lottery.
More information on the results can be found online at bristolavonriverstrust.org/waterblitz and anyone who wants to volunteer or ask questions about the project should email firstname.lastname@example.org.
Picture: Collecting samples for this year's WaterBlitz