Stiffkey Integrated Constructed Wetland

An Integrated Constructed Wetland (ICW) has been created on 15ha of land in the Stiffkey catchment to provide a sustainable, low-carbon, natural wastewater treatment system that will also boost biodiversity.

Pollution threatens the health of the River Stiffkey, with catchment-wide issues affecting water quality from sources including Water Recycling Centre (WRC) effluent, intensive agriculture, sediment run-off and septic tanks. The Stiffkey is currently rated at ‘moderate’ ecological status (Water Framework Directive, 2019), and there is an aim to achieve ‘good’ status by 2027.

A Nature-based Solution

The 1-ha, 3-celled ICW will provide natural filtration of effluent discharged from an existing WRC before it enters the Binham Stream (a tributary of the River Stiffkey). Although within permitted levels, the effluent contains pollutants (principally phosphate) that can lead to eutrophication and can be detrimental to freshwater ecosystems.

The wetland has been carefully designed to blend into the surrounding environment; each cell will be planted with native wetland plants – including veronica, marsh marigold, rush, watercress, iris and sedges – to kick-start the removal of nutrients. Furthermore, the ICW will deliver multi-benefits as a nature-based solution: the creation of a richer, varied habitat that will remain wet throughout the year will enhance local biodiversity and act as a carbon sink.

A new river channel

To further enhance the site, a 400m section of the heavily-modified Binham Stream has been restored to its natural, meandering state. The channel has been reconnected to its floodplain, providing it with the space it needs to mitigate the risk of high flows downstream.

This work was completed as part of the ‘Norfolk’s Two Chalk Rivers – Restored, Revitalised, Resilient’ project, funded by the Government’s Green Recovery Challenge Fund and delivered in partnership with the Norfolk Coast Partnership. Additional funding was received from the Environment Agency, the WWF and Finish partnership, The Coca-Cola Foundation and Anglian Water.

With thanks to the landowner for supporting the project, as well as William Morfoot Ltd for the construction.