The Environment Agency has downgraded the bathing water rating of a popular Devon beach from ‘excellent’ to ‘good’ following a one-off spike in bacteria levels.

Shaldon Beach had previously held an ‘excellent’ rating since 2016. However, a brief period of heavy rain in the summer that coincided with an official Environment Agency test saw bacteria levels in the River Teign dramatically exceed the recommended safe levels.

Campaign group Friends of the River Teign believes the spike in bacteria levels seen in the test was an isolated incident and that the water quality over the summer months was genearlly excellent due to the warm, dry and sunny weather.

‘It was very disappointing to see that at the height of a really busy and enjoyable summer on our beaches, a single storm of rain has reduced the overall water quality rating at Shaldon,’ commented Friends of the River Teign chair Stuart Reynolds.

The group, which carries out its own water quality testing throughout the year, said local rainfall data showed that around 10mm of rain fell over a couple of hours on July 31. The downpour is likely to have triggered a ‘first flush’ of a number of South West Water storm overflows near beaches. The dry ground would have also increased run off from agricultural sources and roadside storm gullies.

‘In one 10-minute period, 4.2mm of rain fell and, by chance, this coincided almost exactly with the time that the Environment Agency carried out its routine, randomly scheduled tests,’ a Friends of the River Teign spokesperson said.

Data obtained by the group suggest that, on average, this level of rainfall occurs around three or four times a year. ‘We have seen similar results in our own testing, so we know that this does happen when it rains heavily,’ the group said. ‘However, these infrequent events are very difficult to predict and not always picked up by official tests.’

Because the rainstorm was so localised, neither the Environment Agency nor the Surfers Against Sewage app, which relies on data from South West Water, provided any warnings about a potential dip in water quality despite a number of sewage overflows operating at the time, Friends of the River Teign pointed out.

The group shares its own data with the Environment Agency to assist with investigations. Previously, Friends of the River Teign had flagged high bacterial levels at Bitton Brook, which resulted in the Environment Agency locating a misconnected sewer that was discharging into the river Teign. The group has also engaged with local stakeholders, including Teignbridge District Council, Parish councils and local MP Martin Wrigley, about the incident.

‘We are very much hoping that the Environment Agency investigation will trigger some much-needed improvements in both the local sewage infrastructure and the warning system,’ Friends of the River Teign said.

The group is also looking at ways to improve water quality information, including real-time testing of bacterial levels. ‘The current testing arrangements rely on a set number of random tests each year and will often miss events such as these. It is important not to read too much into one year’s figures, or a single event but, equally, it is vital that we learn the lessons when they do occur.’