It’s Gravel Time! Repairing our chalk stream

Not many people know that we have an internationally rare and important habitat on our doorstep here in Abbey: Coldham’s Brook, a chalk stream, runs through our ward. Chalk streams are internationally rare habitats. They provide habitats for many significant species, including brown trout and water vole. About 85% of the world’s chalk streams are in the UK, mostly in the south and the southeast of England.

Chalk rivers emerge from the chalk aquifer, the pure water is rich in minerals and remains a relatively constant temperature year-round. This means it is great place for a variety of water plants to grow, including water-crowfoot and water star-wort. A good variety of plants and good water quality supports many invertebrate and fish species.

In Cambridge, Bin Brook, Cherry Hinton Brook, Coldham’s Brook, Hobson’s Brook and Vicar’s Brook are all chalk streams. The chalk aquifer they emerge from, to the southeast of the city, is a main source of water for much of the water we use in Cambridge. Using less water, particularly in warm, dry summers, leaves more to support the environment. Check the Cambridge Water website for information about why you should save water.

We’re excited to be working with Cambridge City Council on a project to help conserve it for future generations. The project is funded by The Pebble Fund, CamEO (Anglian Water) and Cambridge City Council.

At the end of May we had a successful workday to improve water flow, planting marginal plants in the brook, introducing gravel for gravel beds, and repairing the bank!

You might have noticed some of the changes already. Do have a look when you walk along the most southern section (running through Barnwell Nature Reserve along Coldham’s Common down toward the Sainsbury’s Roundabout).

We’ve had three successful volunteer events so far and you’re invited to the next one on the 24th September 2022 for World Rivers Day – if you’d like to get involved email: or pop into the Hub to let us know.


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