Surface waters are categorised into different types according to their physical and chemical characteristics. The types indicate, in very general terms, the sorts of plants and animals likely to be present in undisturbed conditions.
The characterisation process has identified 21 different types of river in England and Wales.
The typology is based on catchment size, altitude and geology. We have reviewed our river water body network since the publication of our Article 5 reports in 2005. We have now increased our network to include missing General Quality Assessment (GQA) lengths, drinking water protected areas and freshwater fish sites.
Lakes have been identified by using a criteria which include their altitude, latitude, depth, geology (physical appearance) and size.
For the Water Framework Directive, we are looking at lakes with surface areas greater than 50 hectares, however some have been included that are smaller where they are deemed to be of conservational significance.
Estuarine and coastal waters
The typology for estuarine and coastal waters was based on latitude, longitude, salinity, and tidal range.
We also looked at wave exposure for coastal waters and depth for estuarine waters. We have also included some saline lagoons of special scientific interest to our estuarine and coastal water bodies since Article 5 due to their biodiversity significance.