Integrated management of the raw water transfer invasion pathway

Abstract

Raw Water Transfer (RWT) schemes move large volumes of freshwater between separate waterbodies via complex infrastructure networks, and are a pathway of freshwater invasive non-native species (INNS) spread in most nations globally. Environmental regulators in England and Scotland have recently introduced progressive policies outlining requirements for pathway stakeholders to manage RWTs. This is a positive step; though no known management methods currently exist, and the development of effective methods will be a long and challenging process. Additionally, under the current policy, not all RWTs will have to be managed. Multilateral stakeholder collaboration and co-ordinated action is therefore needed to deal with the invasion risk posed by the ever-increasing number of RWTs. RWT information is disparate and difficult to access in Great Britain however, and the INNS management community remains generally unaware of the pathway. We therefore present information to illustrate the scale and prevalence of RWTs in England and Wales, and highlight that many of the approximately 162 major RWTs (> 45 million litres/day) in England and Wales cross Water Framework Directive management catchments and river basins boundaries, and in some cases political borders. We discuss the consequent need to integrate RWTs into well co-ordinated surveillance and management plans at multiple scales, and explore options to improve information access and stakeholder collaboration, in support of improved management efficacy and the attainment of national INNS targets.