This dataset is a subset of "WFD Classification Status Cycle 2" and contains classification data for phytobenthos in lakes. Phytobenthos or diatoms can be used to indicate the ecological status of a lake. A biological index called the Trophic Diatom Index (TDI) is calculated 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 lake 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. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved.