Chalk streams
One of the rarest habitats on Earth to remember when you brush your teeth!
The story so far.....share your thoughts and photos about chalk streams along The Ridgeway to help us create a community Top 50!
From the chalk bedrock of the hills along The Ridgeway, groundwater feeds chalk streams that are internationally rare habitats but commonplace to local residents. Crystal clear water, Brown Trout, Kingfisher, Water Vole and white-flowered Water Crowfoot are a sign of a healthy chalk stream. Unfortunately, these chalk streams compete for water in an area where human consumption is higher than the UK average and climate change brings increased drought. Read on below to find out more….
Banner image of Water Crowfoot. Credit: Steve Daniels, Wikicommons
Kingfisher. Credit Frank 2.0
Gathering watercress at Letcombe Bassett 1939 Credit Edward George Malindine Daily Herald Science Museum Group
Old watercress beds Letcombe Bassett Steve Daniels Wikicommons
River Og near Ogbourne St Andrew. Credit Brian Robert Marshall
River Og near Ogbourne St Andrew. Credit Brian Robert Marshall
Reduce your water use by Chilterns Chalk Streams
It is easy to miss the River Og as The Ridgeway passes over it near Ogbourne St George in Wiltshire, but it is an example of a rare chalk stream. Sometimes it can dry out because water levels in chalk streams reflect the fluctuations in groundwater held in the chalk aquifer (see photo gallery above). This video explains how this works and other special characteristics of a chalk stream. Flowing south, the River Og meets the River Kennet near Marlborough and the Kennet is a particularly special example, protected as a Site of Special Scientific Interest. The Kennet can be traced upstream to one or more sources around the end of The Ridgeway in the Avebury World Heritage Site, one of which is the Swallowhead Springs which has strong spiritual associations.
Unlike rainwater which flows across the ground to enter watercourses, groundwater from the chalk aquifer has been filtering for years through cracks and pores in the bedrock and so it is clean of pollutants and rich in minerals. Groundwater also remains at a fairly constant temperature year-round too, providing stable conditions for plants and animals living in the stream. The clean water of the springs of the Letcombe Brook, north of The Ridgeway in Letcombe Bassett, gave rise to a local industry of growing watercress. In the 19th century, watercress was grown in specially constructed beds (see image gallery above) and Letcombe Bassett became famous for “Bassett Cress” sold in Old Covent Garden Market in London.
All chalk streams have been modified in some way, usually for milling, fishing, irrigation or watercress beds, but today’s unprecedented water consumption in combination with climate change is a major threat to chalk streams. Parts of the Chilterns has the highest water use in Europe: 173 litres per person per day. This is more than 30 litres per day above the UK average! Development and population growth will only increase the amount we take and so the Chilterns Chalk Stream Project is promoting ways to reduce water use (see image gallery above). Just think….when you turn off the tap whilst brushing your teeth or keep water in the fridge to avoid waiting for the tap to run cold, your chances of seeing a Kingfisher are greater!
Notes: More information about chalk is available in other Top 50 entries (not all Top 50 entries will be available until end of December 2023).