Using knowledge about how certain substances, such as one of the main pigments of the phytoplankton (Chlorophyll a - Chl a) alter the colour of the water, these parameters can be derived from optial Earth Observation (EO) satellite sensors. Water Insight provides monitoring services of Chl a based on EO data which is validated with in situmeasurements. Also the maps of WFD phytoplankton biomass status classes are created, by application of the WFD tresholds on Chl a as a proxy for phytoplankton biomass. The maps are made available in a portal, which allows to follow the lakes in time, zoom and download maps and time series.