Species checks begin at Sudbury’s River Stour to help drive improvements to water quality for public use

A new project to gauge insect populations in Sudbury’s main waterway is under way, as part of efforts to improve the river’s health and its suitability for human use.

Volunteers from the River Stour Trust and Foxearth Meadows staged their first species sampling session on Thursday, on water around 100 yards below a sewage outlet.

Each month, samples will be collected from different parts of the River Stour to determine a baseline for the populations of species, such as dragonflies, damselflies, mayflies and Caddis flies.

Once a baseline is established, any fall below this would alert the Environment Agency, which must then investigate if pollution may have caused the population decline.

Using equipment funded from the locality budget of Sudbury councillor Jessie Carter, the scheme is part of the Riverfly Partnership – a national network monitoring invertebrate life in rivers.

It comes as the River Stour approaches the end of its first season as a designated bathing water, which requires weekly quality monitoring between May and the end of September.

John Kemp, of the River Stour Trust, said their efforts are both raising awareness, and applying pressure on the relevant authorities.

“The idea is that these little creatures are the canaries of the river system,” he told the Free Press. “If they’re in trouble, so is the rest of the river.

“We count the numbers of individual species and give each of them a score. That enables you to set a baseline for the river.

“If the numbers fall below that, the Environment Agency is required to come out to investigate possible pollution.”

Earlier this year, a stretch of the River Stour by Friars Meadow was granted bathing water status after a year-long campaign.

The Environment Agency now publishes results from water quality monitoring it conducts each week during the bathing season.

Mr Kemp, who co-ordinated the campaign, explained this new collaboration with the Riverfly Partnership would provide an additional check on the river’s long-term health.

He added that the River Stour Trust’s relationship with Anglian Water has been positive so far, with the water company pledging support in its five year-plan.

“One of the reasons we chose this site first is it is only 100 yards below the sewage outlet,” said Mr Kemp.

“We shall be taking another sample above the sewage outlet, which should give us a good check if there is a difference between the two.

“The fact of the matter is, there has been a serious decline in the number of invertebrates in rivers. You don’t see the cloud of mayflies that you used to see in the summer.

“This is a way of raising awareness, and we’re all doing our bit. We will be doing these tests monthly.

“We are seeing a growing awareness of the fact that the river is being monitored, and people are happy about that.”

Despite fluctuating weather over the summer, the River Stour is known as a regular spot for swimmers, canoeists, kayakers, paddle boarders and other users.

Mr Kemp stated that the River Stour’s weekly tests had shown “fairly positive” results in its first bathing season, with the main outliers during heavy rain, where pollution levels briefly rise due to run-off.

This has led to cautious optimism for a good first overall rating, when the river is classified by the Department of the Environment, Food and Rural Affairs (Defra).

“We need to see what happens between now and the end of September, when the testing stops,” added Mr Kemp. “If we get a good rating, it would be really quite extraordinary.

“There were only two or three inland rivers before us which got this designation and, three years down the line, they are still regarded as not suitable for swimming.

“If we were to get even a satisfactory grading, it would be a significant advance for wild swimmers in Suffolk.

“I do know that many of the people who were made aware of our application last year have become regular swimmers, and have continued.

“At the moment, the sewage works is designed to produce water of second-grade classification – meaning it is suitable for ecological purposes, but not for humans to go swimming in.

“By the time it gets down to Friars Meadow, it has become diluted enough that it is suitable for swimming.

“Anglian Water did say in its five-year plan that, if we got our designation, it had provision for additional measures to be taken.

“So far, our relationship with Anglian Water has been positive, and I would hope it would continue to be so,” he added.