River restoration
The River Wandle was once the most famous chalkstream in England, and skilled fishermen used to travel from far and wide to pit their wits against the huge, wily trout that lived in its clear waters.
Some, like Lord Nelson, loved it so much that they bought houses along its banks. William Morris produced his famous Arts & Crafts fabrics at Merton Abbey Mills, and caught perch from his factory bridge beside Merton High Street. Frederick Halford discovered dry fly fishing in Carshalton, and spread the technique to the Test and Itchen where it became one of the sport’s most hallowed traditions.
During the 20th century, the river was very heavily engineered to make it more efficient as a flood channel. In many places it was given vertical concrete sides to make the most of building land along its banks, and it was even buried completely in some parts of Croydon and Wandsworth.
At the Wandle Trust, we now believe that the time is right to start the ground-breaking work of restoring long stretches of the Wandle to true ecological health. Thanks to Thames Water, the quality of the water is some of the best in London, and there are large populations of freshwater shrimp and other invertebrates for fish to eat.
We also know that significant numbers of our “Trout in the Classroom” fry are surviving and growing to maturity – another indication of the Wandle’s potential, even in its unrestored state.
Like the proverbial canary in the mine-shaft, trout are an indicator species that can tell us how healthy their environment is. If trout can survive and thrive, even in an inner city, this reveals that the habitat may be good enough for threatened species like water voles and otters – as well as many other birds and insects.
In late 2005 we commissioned a survey of the whole river from the Wild Trout Trust. Walking the full length of the Wandle in two days, their expert surveyor helped us identify ten stretches which would benefit from more restoration – ranging from a shallow area of gravel just below Carshalton Ponds, to the reinforced banks alongside Merton High Street and Garratt Lane.
For instance, hard-sided areas of steel sheeting or concrete could be softened with meandering low-level rolls of coconut fibre, planted with native vegetation – or indeed broken up with boulders, as the Environment Agency have already done near Plough Lane (see picture above).
Where there are too many trees overhanging the river, some of these could be thinned and recycled into current deflectors, allowing more light into the river-bed so that water-weeds like ranunculus can flourish and provide even more habitat for insects and fish. This is exactly what we’re now planning to do at Hackbridge, helped by a very generous conservation bursary from our partners at the Wild Trout Trust and fishing tackle manufacturers Hardy & Greys.
In the meantime, we’re also working closely with the Environment Agency to decide what to do about the many weirs that still remain from the Wandle’s industrial past, and are now preventing migrating fish and other species from moving freely along the river.
If you’d like to get involved with our river restoration work, or help us raise funds for one of London’s most vital biodiversity projects, please let us know.