This report is part of a project that aims to to identify priority river habitat using nationally available data within a GIS environment, focusing on naturalness and natural processes as the primary criterion. Maps and associated GIS layers will be produced for use in operational decision-making, including within the river basin management planning process and in agri-environment targeting. It is a collaboration between Natural England and CEH, with support from the Environment Agency. It reports on the initial revisions and proposals for on-going refinement of the priority river habitat map and follows on from JP006, Priority river habitat in England – mapping and targeting measures.