Cartogram of monitoring stations density, aggregated by National River Basin Districts (RBDs, e.g. Donau, Oder, Elbe, Rhine, ...) is displayed within defined classes. The National RBDs are coloured according to the density of all WISE SoE stations used for reporting monitored values in this context. The monitoring stations used for characterizing chemical and ecological status of river water bodies in reporting to the Water Framework Directive may not necessarily be based on the same set of SoE stations. In less detailed scale, data is aggregated by RBD when in more detailed scale individual stations appear in shape of triangles. Additional information are provided in pop up windows which can be activated with a click on a station.Historical data (from 1992 on) can be displayed and viewed with time slider tool.