Operational catchments are a way of grouping Water Framework Directive (WFD) waterbodies together at a meaningful scale smaller than the management catchment or River Basin District. The river waterbodies are not always hydrologically linked as they may have been grouped based on pressures and measures. This data set is based on the surface water boundaries of operational catchments and excludes the underlying Groundwater data. Attribution statement Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved.