River restoration: partnership projects

Here at the Wandle Trust, we believe that the 5-year Living Wandle project represents a unique opportunity for many different organisations to come together and work in close partnership to secure the healthy, sustainable future of this very special urban chalkstream.

During the 19th and 20th centuries, many parts of the Wandle were heavily re-engineered – firstly for the benefit of the 90 mills that once lined its banks, and then to increase its efficiency as a storm drain, carrying as much water as fast as possible out to the Thames.

Fortunately, times have changed, and the emphasis is now on recreating biodiversity, restoring natural features, and helping the river itself to moderate high and low flows.

Despite localised over-nutrification, the effects of urban run-off, and massive  abstraction from the aquifer that supplies its headwaters, the quality of the Wandle’s 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 at least 10 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 “green walls” and meandering low-level rolls of coconut fibre, planted with native vegetation – or broken up with gravel and boulders, as the Environment Agency have already done near Plough Lane. 

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. 

The flow deflectors will also help to re-energise sluggish currents, scour silt, and re-sort the river gravels. This is exactly what we’re now doing at Hackbridge, helped by a very generous conservation bursary from our partners at the Wild Trout Trust and fishing tackle manufacturers Hardy & Greys.

We’ve also been working closely with the Environment Agency to decide what to do about the many weirs and hard structures that still remain from the Wandle’s industrial past, and are now preventing migrating fish and other species from moving freely along the river.

But most significantly of all, we hope that the ongoing scientific and social research for our Community Catchment Plan will soon reveal exactly what projects we need to prioritise with our partners to make the Wandle truly sustainable for the future.

If you have any ideas, or if you’d like to get involved in this vital habitat work as part of the Living Wandle project, please don’t hesitate to get in touch!