Why chalk streams matter
Our Rivers on the Edge project initially focuses on the River Kennet, the Upper Lee and the Itchen, three of England’s iconic chalk streams – fragile, beautiful and unique river systems with an abundance of native wildlife.
Why are chalk streams special? The rainwater that soaks through chalk ground becomes alkaline and rich in nutrients, and cooled by its journey through the chalk, so when it emerges it’s at a constant temperature, summer or winter.
In natural circumstances, chalk aquifers also help buffer impacts of flood and drought.
These lush rivers provide a perfect, gentle habitat in which everything grows abundantly – insects, water plants, fish (including trout and salmon), crayfish, birds and mammals like the water vole and otter.
As you might know, Kenneth Grahame’s classic book The Wind in the Willows was famously written beside an English chalk stream.
Rivers under pressure
Since Roman times, chalk stream channels have been progressively modified, for navigation, transport, agriculture, landscaping and milling.
In the 20th century a sprawling suburbia demanded more and more water. Drilling technology improved and deep boreholes were sunk.
The effects of abstraction have spread, and today there’s barely a chalk stream left that doesn’t feel its impact – in some cases a deadly impact.
All the rivers identified in the Rivers on the Edge project supply millions of litres of water per day – and all are officially classed as “over-abstracted” by the Environment Agency.
By 2020, increasing population will mean total demand for water is likely to be around 5% higher than today – that’s an extra 800 million litres of water per day.
And of course climate change scenarios suggest river flows in late summer and early autumn may reduce by as much as 80% by 2050, with a 15% reduction in total annual average flow.
Unsustainable abstraction is something we can tackle immediately and urgently, which is why it’s the focus of Rivers on the Edge.
We hope that by highlighting these rivers, we can encourage everyone to recognise and deal with the issues before it’s too late.
We also have legal obligations to protect our water supply – under EU directives and government targets – as well as the environmental and social reasons.
Apart from anything else, imagine no more fishing or boating, no leisurely walks along river banks on a Sunday...
The Kennet
The River Kennet is the main tributary of the Thames, accounting for over half its flow in summer months. It springs from the chalk of the North Wessex Downs and flows through rolling Wiltshire countryside before meeting the Thames at Reading.
The upper Kennet is a wonderful example of an English chalk stream – part of it is designated a Site of Special Scientific Interest because of its important ecology.
But we also depend on it for our water.
For instance, the town of Swindon relies on the Kennet to supply up to 30,000 homes.
This abstraction can be especially damaging as it’s taken from the sensitive upper reaches and, since it’s not returned to the catchment as treated sewage, it represents a net loss of water.
The Kennet also shows signs of extensive human intervention and re-shaping – some stretches of the riverbed are too wide for the flow.
The Og, a Kennet tributary, is remembered by older locals as a stream they swam in, but now, in places, you can walk on the river bed without getting your feet wet.
How Rivers on the Edge will help
We'll be working with local group Action for the River Kennet to help restore upper reaches of the river, and with Thames Water to help improve water efficiency in the houses that depend on the Kennet for thier supply.
The Upper Lee
The Lee has been a key source of London’s water for centuries.
The Upper Lee and its chalk stream tributaries, the Mimram, Beane, Ash, Rib and upper Stort, flow through Hertfordshire and Bedfordshire, providing water to towns like Luton, Stevenage, Welwyn Garden City and Hertford – with 200 licensed abstractions.
The dwindling flows are supplemented by outfall from sewage works, which, during low flows, can make up the bulk of the water in the main river. Sometimes the Mimram and Beane can dry out completely (as the photo of the Mimram above shows).
How Rivers on the Edge will help
We'll focus on the rivers Beane and Mimram, two tributaries of the Lee, which are badly affected by over-abstraction, and will be working with local MPs and partners such as the Beane Restoration Society and Friends of the Mimram.
The Itchen
The River Itchen is perhaps the most iconic chalk stream in the world. It springs from the chalk south downs at Arlesford near Winchester and winds its way south to the Solent at Southampton. In its upper reaches the Itchen remains one of our most unspoilt chalk streams.
The Itchen supplies half a million people living in the towns and cities grown up on its banks, including Winchester, Eastleigh and Southampton, and flows through areas earmarked for substantial housing growth.
The Itchen is also home to England’s water-heavy watercress industry, as well as trout farms and prime arable and livestock farmland.
How Rivers on the Edge will help
We'll be working with local partners including the Hampshire and Isle of Wight Wildlife Trust to help identify problems and solutions for the Itchen and Meon.
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Download the full report
Rivers on the edge report
Our partners
WWF would like to acknowledge support and input from:
Action for the River Kennet
Artesia Consulting
Hampshire and Isle of Wight Wildlife Trust
Charles Rangeley-Wilson
Waterwise
Professor Rob Wilby, Loughborough University