New project launched to save river from sewage

A new project has been launched to help people improve a local river by reducing the amount of sewage being discharged into the waterway.

The Save Water to Save the Trym (SWST) project, part of the Sea Mills and Coombe Dingle Climate Action Group, has got underway in north Bristol.

The focus is on the Trym and also Hazel Brook, the waterways which flow from Cribbs Causeway and Southmead, reaching the Avon at Sea Mills.

Nikki Jones, the chair of SWST, said: “The problem is that, during times of rainfall, too much rainwater is draining off our roofs, roads and drives, and straight into the sewer system. When the underground pipework is overloaded, the combined sewage overflows discharge.”

Data from the Rivers Trust shows that there are 29 identified combined sewage overflows which can potentially discharge raw sewage into the river. This happened for more than 700 hours in 2021. Even in 2022, a year with less rainfall the total was 399 hours.

The Save Water to Save the Trym (SWST) project has been launched to reduce the amount of sewage being discharged into the waterway – photo: Nikki Jones

Sewage in the river harms its ecology and threatens wildlife, but local volunteer groups have sought to improve this over the last few years.

The Trout in the Trym group has for example cleared rubbish and invasive plants from the river.

Brown trout and eels have been seen in the river and evidence of otters has been found, with spraint – or otter poo – proving that otters are using the river on a regular basis.

Peter Coleman Smith from Trout in the Trym said: “Quite recently we have had a visit from the Bristol Otter Group and they have been saying they have been finding spraint.”

Peter has walked the lower part of the river himself with an ecologist from Bristol Avon Rivers Trust and they found “loads of spraint all over the place, everywhere you would expect to find it”.

There are also fewer trout this year than last which Peter suggests is because the otters have been feeding on them.

For the current level of wildlife to be maintained and improved, the sewage issue, which comes under the remit of Wessex Water, needs to be addressed.

Sewage is harming the ecology and wildlife of the River Trym, pictured after a downpour in July 2023. Photo – Nikki Jones

A Wessex Water spokesperson said: “Separating rainwater from sewage is the most environmentally friendly way to reduce how often storm overflows automatically operate, so we applaud the Sea Mills and Coombe Dingle Climate Action project and we’re in contact with the organisers to discuss how we can work with them.

“Wessex Water is already investing £3 million every month on storm overflow schemes and, if approved by out regulators, will increase this to £9 million per month from 2025. Schemes include increasing sewage treatment capacity at our largest water recycling centre in Avonmouth.

“We currently have more than 50 sewer flow monitors in the Trym catchment which will help us develop further options to improve storm overflows in the area.”

But Nikki feels that Wessex Water’s action will not come soon enough and hopes a community action led by SWST will make a more speedy impact.

She wants to help householders hold back as much rainwater as possible by using water butts to harvest rainfall.

When SWST surveyed local people in Sea Mills, more than 80 per cent said they would like a water butt, or to extend a system they already have.

But for most people this was a low priority, with time and cost both barriers to acquiring and setting one up. SWST is offering advice and also financial and installation help if needed.

SWST is currently crowdfunding for support and every pound raised is being matched by the Save our Wild Isles Community Fund. With this support almost £3000 has been raised in just two weeks.

Mary Milton is reporting on Sea Mills as part of Bristol24/7’s community reporter scheme, a project which aims to tell stories from areas of Bristol traditionally under-served by the mainstream media     

Main photo: Nikki Jones

Read next:

• River Trym causes a stink
• Latest plans to restore hidden river in south Bristol
• Citizen science project returns to clean up Bristol’s waterways

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