A quantification of gypsum load in the samplig stations of the Ebro river network during the hydrological period 1970-85 has been carried out. The gypsum load has been calculated from the data sets available trouhg a load computation procedure for each one of the 68 samplins stations. In each of these, the surface area occupied by gypsiferous lithofacies in the catchments has been planimetered. It can be stated in general terms that the gypsum load in each catchment depens directly on the surface area that the gypsum occupies and on the volume of water supplied.Peer reviewed