Real-time monitoring to protect chalk stream

BBC A man wearing a life jacket and waders stands in the River Test preparing to place a water quality monitor on the riverbedBBC
Recent pollution incidents led to the project to constantly monitor water quality along the length of the River Test

A scheme to provide real-time pollution monitoring along the entire length of a chalk stream is believed to be the first of its kind in the country.

Nearly 20 sensors, known as sondes, have been placed into the River Test to continuously measure key indicators of water quality.

The collaboration between Southern Water, local communities and campaigners follows recent concern over pollution levels.

It's hoped the continuous monitoring will give a better understanding of the types of pollution and where and how it's entering the river.

A hand wearing a blue glove holds a long black cylinder underwater with a cable attached to the rear
Each monitor contains probes which sample specific indicators of water quality and pollution with the data sent back day and night

"We have, from source to mouth, the entire River Test and major tributary areas covered by this monitoring equipment" explains member of the Pan Parish River Pollution Forum and local Lib Dem councillor, Geoff Cooper.

"As far as we know it's never been done before in the UK and that's why it's such a ground-breaking and exciting moment."

The monitors provide half hourly updates of dissolved oxygen, ammonia and water temperature levels. The information can be accessed by campaigners and river keepers alike.

It's hoped within the next year it will also be available to the public.

White clouds hang in a blue sky above a section of the River Test with green weeds in the clear water
The River Test is the longest chalk stream in the UK rising at Ashe near Basingstoke and flowing 40 miles to Southampton Water

"I've been a river keeper in Hampshire for 10 years but I grew up looking after a river in Yorkshire" says Seth Crosswaite, river keeper at Houghton Lodge.

"What you want to see in a chalk stream is nice clean gravel. That's what the fish need to spawn on."

"All those monitors down that river will measure it in real-time. So if we get a pollution incident we can look above stream and down stream of it. Above stream to see where it is and downstream to see what effect it is having on the river."

Concern about the health of the River Test grew in 2024 when heavy rain saw overflow sewer outlets spill into the river during what Southern Water called "exceptional circumstances".

In March that year hundreds of campaigners and residents protested outside the company's Fullerton Waste Water Treatment Works.

According to Geoff Cooper that protest proved a turning point.

"That made Southern Water realised just how angry people were."

"They opened their doors to us and gave us the opportunity to work collaboratively together to find solutions to better understand the quality of our rivers."

Southern Water says it's investing 84 million pounds improving water quality on the Test - 28 million pounds at Fullerton Waste Water Treatment Works.

The company says the voluntary monitoring scheme puts it ahead of the game and prepares the way for forthcoming legislation.

Scores of silver fish hug the gravel river river bed as the sunlight creates a vivid blue colour in the waters around them
The River Test is world famous for fly fishing and an internationally important habitat

"It will look at inputs from not just our assets but from all other sectors that operate along the river corridor such as agriculture" explains Joff Edevane, Environment and water quality lead for Southern Water.

"The sondes give riverkeepers joined-up daily insight into what's affecting water quality in these rivers, which is a great starting point to be able to improve it.

"This isn't just about our outfalls - numerous factors affect water quality, from agricultural runoff to illegal connections. But we know we need to do better when it comes to discharges and storm overflows."

For local residents, campaigners and river keepers alike it's hoped the new monitors will play a crucial role safeguarding a much loved and prized chalk stream.

Geoff Cooper hopes a better understanding of the challenges it faces today will help protect it for years to come.

"The River Test is the gold standard of chalk streams and it's crucial that we, as custodians of it, do everything we can to protect it for future generations.