The WISP-3 is a hand-held spectro-radiometer, which measures the light that is reflected from a water body. From these measurements, water quality parameters such as the concentrations of chlorophyll, phycocyanin and total suspended matter can be derived. Within AQUA-USERS, there are five WISP-3 instruments used by the project partners and users. The users will take measurements at their production sites and get instant readings of water quality parameters. These data will assist them in taking the best possible management decisions. The project partners will additionally use the spectral readings of the WISP-3 for validation of satellite data for water quality monitoring.