Chalk streams rise from springs in chalk bedrock, which is known as the aquifer. The porous chalk allows water to seep through quickly, removing organic matter and sediment. The result is very clean and clear water that support a unique array of wildlife.
Most of the world's chalk streams are in southern England, particularly in East Anglia. Hobson’s Brook and Cherry Hinton Brook are to well-known examples in Cambridge.
These rare ecosystems are important for their ecological value. The streams’ stable temperature and mineral-rich water support unique plant and animal communities.
Economic and urban growth and climate change put pressure on these delicate habitats. Chalk streams face many threats:
- Pollution and sewage from agriculture and industry can damage water quality and biodiversity. Water draining off nearby roads and buildings, known as runoff, also has a negative impact.
- Sedimentation and erosion can degrade the habitats of plants and animals that live in chalk streams. These are often caused by poor farming practices.
- More water leaving the aquifer than is naturally replenished can be a problem. This over-abstraction can be caused by farming or taking it for water supply.
- Invasive non-native species like American signal crayfish and Himalayan balsam can disrupt the streams’ ecological balance.
- Urban infrastructure development can destroy or fragment the habitats.
- Chalk streams have not been fully mapped, which complicates conservation efforts. There is also currently not much data about biodiversity or water quality in the streams.
Protecting the city’s chalk streams
We need proactive measures to protect local chalk streams. These include regenerative farming practices and riparian restoration projects. Long-term collaboration and evidence-based plans are essential to preserving these ecosystems.
We have formed the Greater Cambridge Chalk Stream Project to address these challenges. Other organisations involved include local parish councils, utility companies and government agencies.
The project’s evidence-based plans will help restore and protect our chalk streams. Its work will help to:
- increase biodiversity
- introduce sustainable water management practices
- support communities to enhance and sustain their local environment
Other projects
The Catchment Based Approach initiative works to improve the natural value of our environment. Their chalk stream strategy calls for giving the streams enhanced environmental status. It aims to protect, enhance, and restore them by improving water quality, managing abstractions, and restoring habitats.
