The dataset consists of occurrence data of the aquatic organism groups fish, macroinvertebrates and macrophytes that were sampled in the German federal state North Rhine-Westphalia between 2004 and 2009. The sampling was conducted according to the protocols of the national monitoring programme for implementation of the Water Framework Directive. More information on this dataset can be found in the Freshwater Metadatabase - BFE_91 (http://www.freshwatermetadata.eu/metadb/bf_mdb_view.php?entryID=BFE_91).