PROJECT

Upper Wandle Restoration – a prize-winning project

The South East Rivers Trust restored the Carshalton Arm of the Wandle, making it the first river in London to achieve ‘Good Ecological Potential’ under the EU Water Framework Directive.

The Trust opened up fish passage, enhanced river habitat, and addressed urban pollution, creating a thriving river with brown trout beginning to reproduce successfully for the first time in over 80 years.

In recognition, the project is the proud winner of the Urban Category for the 2016 UK River Prize.

River Wandle: View 3 after River Wandle view 3 after © South East Rivers Trust
River Wandle: View 3 before River Wandle 3 before © South East Rivers Trust
River Wandle: View 2 before River Wandle before © South East Rivers Trust
River Wandle: View 2 after River Wandle after © South East Rivers Trust
River Wandle: View 1 after River Wandle 'after' © South East Rivers Trust
River Wandle: View 1 before River Wandle 'before' © South East Rivers Trust

  • volunteer hours restoring rivers

    3000

  • metres of river opened to fish passage

    2500

  • metres of chalk stream habitat restored

    500

  • silt traps installed improving water quality

    3

The River Wandle - an open sewer?

The Wandle chalk stream itself is comprised of two branches and our project focused on the Carshalton Arm. Rising from natural springs in Carshalton, this branch joins the main Wandle at Hackbridge.

Just like the main river, the Carshalton Arm was modified to make room for development leaving a river channel with very little habitat. In fact, by the 1960s the Wandle was referred to as an open sewer and all but biologically dead.

 

River Wandle 'before' © South East Rivers Trust

Trout in the Classroom

Between 2000 and 2008, the Trust reintroduced brown trout to the river with school children through our Trout in the Classroom programme (TitC).

TitC gives pupils the chance to raise brown trout from eggs in a classroom setting and then release them into a nearby stream or river, with equipment and guidance provided by the Trust’s expert staff.

 

Trout in the classroom © South East Rivers Trust

Reconnecting the river

The South East Rivers Trust lowered and notched four weirs, improving flow and fish passage.

On the fifth and largest weir, SERT lowered the height by one metre, and modified the existing fish pass to make it more effective.

In total, the Trust opened up 2.5 km of river to fish passage, allowing fish to reach new habitats including clean gravels as spawning grounds. 

Notching a weir to allow fish passage © South East Rivers Trust

Enhancing habitat

Working with nature-based techniques, we narrowed and meandered the river to improve flow and create a low flow channel, making the upper reaches of the Wandle more resilient to climate change.

The riverbed was sculpted with 370 tonnes of gravel to create the perfect spawning habitat for species like the brown trout.

To create further habitat diversity, extensive large woody material was fixed in the channel, as well as 3000 native plants added by volunteers to create marginal habitats.

This work provided habitat for each stage of the trout life cycle, as well as for plants, invertebrates and other wildlife.

Forming a meandering channel © South East Rivers Trust

Improving water quality

Most of the surrounding roads drain straight to the Wandle through three main surface water outfalls so that after rain, all the oils and heavy metals on the roads drain straight into the river.

With no space to install cleansing wetlands, we fitted three Hydrodynamic Vortex Chambers – silt traps – onto the surface water drains, underneath the roads.

These intercepted the water, removed contaminated sediment, leaving cleaner water entering the Wandle.

Installing one of three downstream defenders © South East Rivers Trust

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