City of Trees have undertaken work to improve the water quality of an unnamed tributary of Worsley Brook in Salford, through channel naturalisation, and the creation of wet woodland.
The site is located within a former council tree nursery, known as Cleavleys Nursery. between the M60/M62 interchange and Worsley brook The southern tributary drains land adjacent to a closed landfill site before passing beneath the M60, from which it receives runoff.
Environment Agency monitoring of this tributary, conducted in early 2014, identified contamination with ammonia, and the discharge from the tributary had been contributing to water quality failures within Worsley Brook under the Water Framework Directive.
Why have we taken this approach?
There is growing evidence that allowing the stream to take a more natural course through the woodland will help to breakdown particulates and other pollutants that are being carried into Worsley Brook from the M60 motorway junction. We think this is a cost effective alternative to more traditional, mechanical water treatment.
Also, wet woodland is an important habitat for animals and plants of both woodlands and wetlands. Wet and waterlogged woods provide important habitats for biodiversity with an abundance of lichens, mosses, sedges, rushes and ferns and large numbers of invertebrates which support amphibians, mammals and birds.
Dead wood associated with water provides a specialised habitat not found in dry woodland types which supports craneflies and other insects. These insects, in turn, make ideal food for bats and other priority species like willow tit.
Through this project, we hope to:
What did we do?
City of Trees undertook a package of channel renaturalisation, planting of wet woodland species, public engagement, and improved pedestrian access.
The scheme allows mixed leisure use whilst acting to attenuate highway runoff and capture contaminants before they enter Worsley Brook downstream.
The design was based on audit results, iterative flow path analysis and flood risk. Material excavated from the existing channel embankment was used to create a bund, to ensure that water flows re-enter the original channel and don’t extend beyond the proposed wet woodland area.
A novel approach
This project, which is collaboration between City of Trees, Environment Agency and Salford City Council, is one of the first of its kind in the north of England, and has already gained much interest from people working in the fields of Water Framework Directive, and green infrastructure.
Work has been delivered with the support of Natural Course, a European Union LIFE-IP programme. Natural Course is an integrated approach to water management for the North West of England. Natural Course brings together catchment partnerships across the North West along with the Environment Agency, Natural England, United Utilities, the Greater Manchester Combined Authority and the Rivers Trust.