Land-use changes have repercussions on lake water physico -chemical parameters which impact aquatic communities and lentic ecosystem functions. For sustainable management of lakes, it is necessary to identify ecological thresholds of man -influenced limnological parameters, beyond which ecosystems are not resilient any more and may be considerably modified. A way to detect thresholds is to relate physico-chemical and biological data from a large number of lakes presenting various degrees of human alteration. In this study, a database of more than 300 lakes located in France was analysed, including water quality measurements and community composition of three biological compartments: phytoplankton, macrophytes and fishes. The method of gradient forest was used to detect in environmental gradients some critical zones, where the rate of compositional change of the communities is highest and which can be interpreted as ecological thresholds. It appeared that physico-chemical variables had not the same importance for the three biological compartments. Thresholds were found for various parameters, like total phosphorus or dissolved nitrogen but consistency among compartments was found for only a few parameters, like water transparency. These thresholds will be used for the development of physico-chemical indices of lake ecological status in the implementation of the WFD. Moreover, the statistical modelling of lake water parameters from land use and hydromorphological variables will help to estimate site -specific reference conditions and to identify the most determining anthropogenic factors responsible for the degradation of lake water quality.