Specialist surveyors, working as part of the Cambridge City Chalk Stream Project, are examining five of the city's watercourses: Cherry Hinton Brook, Coldham's Brook, East Cambridge Main Drain (ECMD), Hobson's Brook, and Vicar's Brook. This new project, officially launching in December, builds upon the work of the previous Greater Cambridge Chalk Stream Project. It is a collaboration between the city council and Cambridge Water, supported by up to £1.9 million in funding from Cambridge Water’s Water Industry National Environment Programme.
The surveys will create a detailed inventory of potential pollution pathways by identifying and mapping all visible outfalls and drainage connections, including pipes, culverts, surface water drains, and ditches. This data will establish a baseline to help understand how pollutants enter the streams from roads, urban developments, and industrial areas.
In parallel, the council is conducting extensive water and sediment sampling to investigate contaminants such as heavy metals, hydrocarbons, and tyre-wear chemicals. These investigations are crucial as urban contaminants can be toxic to sensitive chalk stream flora and fauna, disrupt food chains, and accumulate in sediments, causing long-term ecological pressure.
The project aims to understand where pollutants are entering and accumulating, identify the most concerning contaminants, and design effective pollution mitigation measures. This includes exploring nature-based solutions like constructed wetlands and vegetated drainage features to intercept pollution before it reaches the watercourses.
Cllr Martin Smart, Cabinet Member for Nature, Open Spaces and City Services, stated, “Understanding how surface water moves through the city's drainage networks and enters our chalk streams is essential if we are to tackle urban pollution effectively. These surveys will provide us with a comprehensive picture of the drainage connections entering our watercourses, helping us identify potential pollution pathways and prioritise where further investigations and interventions are needed.”
He added, “This is about moving beyond simply identifying poor water quality. We want to understand the sources and pathways of pollution, investigate the contaminants that may be affecting aquatic life and use this scientific evidence to develop effective solutions. Chalk streams are among our most valuable and sensitive freshwater ecosystems. By bringing together detailed scientific monitoring, drainage investigations and nature-based pollution mitigation, we have an opportunity to develop a much more effective approach to protecting Cambridge's chalk streams for future generations.”
