'DEMNA-DNE : Occurrences of Diatoms (Bacillariophyceae) in running waters of Wallonia, Belgium' is a presence-only occurrence dataset resulting of the biological monitoring of surface water bodies carried out by the hydrobiology unit of the Département d'Etude du Milieu Naturel et Agricole and its partners (SPW-ARNE-DEMNA). The diatoms monitoring is running since 2005, in order to assess the trends of the biological status of surface water bodies in Wallonia, together with macrohpytes, fishes and macro invertebrates indicators. The current monitoring network is composed of more than 440 sites, distributed among all streams from the hydrographic districts of the Meuse, the Scheldt, the Rhine and the Seine in Wallonia. The monitoring is ongoing in the context of the EU Water Framework Directive, and thus follows standardised sampling protocols (IPS -Specific Pollution Sensitivity Index, according a methodology derived from the French standard AFNOR XP T90-354). The data has been cleaned for quality issues prior to GBIF publication and thus is not prefectly comparable to the expertised data basis used for the IPS calculation and biological quality reporting. Please feel free to get in touch for any request or return regarding this dataset or the underlying monitoring work.