For all Sardinian lakes the main activities are oriented to study eutrophication and phytoplankton in relation to the use and characteristics of catchment areas, possible disturbances and to the global climate change. The collected data series mainly regard the dynamics of phytoplankton and trophic status, with particular attention to toxic blooms of cyanobacteria, due to the use of water for drinking supplies. In particular the data concerns the main limnological parameters (Secchi depth, temperature, pH, conductivity, dissolved oxygen and saturation, alkalinity, NH4-N, NO2-N, NO3-N, total nitrogen, soluble reactive phosphorus, total phosphorus, dissolved silica, Fe and Mn dissolved) and phytoplankton abundances, as chlorophyll a, cell densities and biomass, class and species composition.