The NADUF-Programme, a long term surveillance of chemical and physical parameters of major Swiss rivers, has now been in operation for over 15 years. Within this programme, water samples (continuously taken, flow proportional) are analysed bi-weekly for biogeochemical substances of natural and anthropogenic origin. Physical parameters are continuously measured and registered. The long-year database permits a differentiated evaluation of the changes in concentration and loads as well as of the factors which influence them. The trends that have been observed for the nutrients phosphate and nitrate are discussed here, as well as the problems and progress associated with endeavours to minimize the nutrient loads.