Background Physical and chemical factors determine the characteristics of the rivers and thus the structure and composition of the biozoenoses. The nitrogen and phosphorus entry from diffuse sources as well as the development of the phytoplancton affected by it are also substantial problems in the inflowing rivers of Saar and Mosel. Punctual measurements have shown that the chlorophyll-, nitrate- and total phosphate- concentrations of these supplying rivers are sometimes higher than the respective pollutant contents of the river Saar. It is therefore important to know the sources of such pollution in order to initiate measures to avoid them. Objectives The key objective of this project was the installation of a system for continuous remote control of eutrophicating substances and of the chlorophyll contents in the rivers Nied and Sauer flowing in catchment areas with highly developed agriculture. Both rivers contribute considerably to the pollution of the Mosel (and in the end of the Rhine) and their catchment areas can be envisaged as good representatives of typical European geographical structures. It seems especially interesting to choose these sites because these rivers are transnational. The information gained should allow a fast validation of the ecological situation and in-time actions and measures of the responsible authorities. The data furnished by remotely controlled measuring stations are therefore to be communicated immediately by telecommunication to the local environmental authorities in the region, where they will be processed and evaluated by a sophisticated software based on statistical and chemometric validation procedures. The monitoring network would deliver a coherent overview of the ecological and chemical status of the waters surveyed and will allow an immediate classification of every kind of surface waters according to their quality. It will be ensured that the control units function in such a way as to comply with the intercalibration of quality factors as it is suggested by the EU. The project aimed to develop a method according to the guidelines of the EU (EU Water Framework Directive 2000/60/EU), which can be expanded to other possible needs in regions with different national legislation within the EU. Results The main result of this demonstration project is the development of a concept and the technical tools for remote controlling systems with special attention to eutrophicating substances from indirect discharges (agriculture). It therefore addresses the problem of diffuse pollution with adequate measuring devices: The eutrophication status of the river is given at any time. It shows as well how fast data communication and evaluation systems can be set up to furnish on-line a status protocol (regarding the physico-chemical water quality) of an ecological system for authorities responsible for the environment . The joint efforts of the associated partners demonstrated the feasibility of an international cooperation in transboundary water quality measurement. The project shows also the differences of national operating systems with respect to legislative standards. The different structures for the authorities can nevertheless interact in a cooperative way to meet the needs of European directives, above all the Water Framework Directive.