Volunteers needed to help find sources of sediment in our rivers

Did you know that rivers carry far more than just water? They also transport solids - tiny particles that float along before settling on the riverbed known as sediment. 

While this is a natural process, many rivers today carry too much sediment, often caused by poor farming practices or erosion of riverbanks. Excess sediment can harm aquatic wildlife, degrade habitats, and reduce water quality. 

And that’s why we need your help! 
 
The CRT is working with the Cam Catchment Partnership and Rothamsted Research to investigate where sediment is coming from and we need volunteers to help.  

We are specifically looking at the Bourn Brook around Lark Rise Farm in Cambridgeshire. 

Conservation Officer Vince Lea said: “Sediment in rivers creates ‘dead’ areas where fish and other wildlife struggle to survive. Too much sediment can block places where fish lay eggs, impair their sight and breathing, and reduce the natural disinfecting power of sunlight. Clean gravel sections of the brook are essential for riverflies and fish species like Bullheads.” 

The project aims to work out where sediment is coming from and this is done with a rather novel method, says Vince. 
 
“To track the sediment, Rothamstead Research use an office document scanner! Volunteers are asked to collect samples of soil from fields, woods and ditches around the catchment area, and also to collect samples from the banks of the brook itself.

"We then collect sediment from the water and from places where it has accumulated in the stream. By scanning the different samples and analysing the image using standard imaging software, such as Photoshop, they can match the sediment that has accumulated in the brook to the most likely area of the catchment that it has come from.”

Regenerative farming practices are all about holding onto the soil but it has been claimed that more intensive farming is losing soil at an alarming rate. The Environment Agency estimates over 2 million hectares of soil are at risk of erosion in England and Wales, while the Sustainable Food Trust estimates 3 million tons of soil are lost each year across the UK. 

There are, however, many other sources of sediment and one of the chief suspects locally is the burrowing activity of American Signal Crayfish. This work will help identify where the main sources of sediment are coming from in the Bourn Brook, and we can then start to work out ways of reducing this problem. 

To help with the project, please see www.rivercam.org.uk/2025/08/04/seeking-help-to-find-sources-of-sediment/ Following this link will give more information and lead you to our collaborator Ruth Hawksley from the Wildlife Trust, who is co-ordinating volunteer activity across the catchment.  

How to support us

If you want to help us protect local wildlife and habitats, you can join as a CRT Friend, attend our in-person and online events and volunteer on one of our farms. You can also sign-up to our monthly newsletter 'CRT News' for regular updates from our farms, straight to your inbox.