This dataset is a subset of "WFD Classification Status Cycle 2" and contains classification data for phytobenthos in rivers. Phytobenthos or diatoms can be used to indicate the ecological status of a river. Monitoring data is run through a classification tool called DARLEQ2 which calculates a biological index called the Trophic Diatom Index (TDI) using information about the environmental preferences of the individual diatom taxa present in the sample. The actual (observed) TDI scores are compared with a predicted TDI score (reflecting a river in pristine condition). The comparison of the observed to expected scores is known as an Ecological Quality Ratio (EQR). EQRs are used to produce a phytobenthos classification (High, Good, Moderate, Poor, Bad) of the water body for Water Framework Directive (WFD) purposes. The data is then run through another tool called VISCOUS to produce a water body level classification. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved.