Weir removal for river restoration; observations on best practice and issues for a lowland UK river

Thousands of small river weirs have been constructed over the last ca. 1000 years or more to provide power for milling and crushing ore, for industrialisation, electricity generation and navigation. Alternative power generation and transportation methods have left many of these structures obsolete and/or derelict. Recently, there has been a drive to create ‘free-flowing’ rivers with fewer or no barriers thereby increasing connectivity and improving ecology. Our first aim was to explore a range of literature and legislation on weir removal in the UK and identify the key benefits and drawbacks in removal that have emerged. We found that ecology was only one of many themes that could be used to justify weir removal or retention. Our second aim was to explore the issues involved with weir removal in a lowland river system in the UK based on the West Sussex Rother where three weirs were being considered for removal. The smothering of ecologically important river gravels by sand trapped behind these weirs and the subsequent release of this sand on removal emerged as a potentially new issue not identified in the literature reviewed. Our third aim was to explore management structures and key stakeholders involved in decision making in the Rother catchment, to establish whether a coordinated approach to delivering weir removal as part of a river management plan could be successfully delivered. We found many official and unofficial organisations have a legal or potentially legitimate interest in the Rother that could produce conflicting evidence for the benefits of weir removal. We conclude that strong leadership and good coordination are required to deliver a successful outcome that requires not only consideration of all the issues involved but which promotes public engagement, and the delivery of an evidence base by monitoring the consequences of any management action.