Analysis of the results of monitoring the quality of surface water is considered in the work. It is based on the use of methods of fuzzy set-assess the status of complex systems, which are described by a variety of parameters. The method allows to determine the probabilistic characteristics of indicators of different nature. This makes it possible to avoid the limitations and ambiguity that arises when the convolution of partial criteria in some global quality criterion.
fuzzy set multi-criteria evaluation, membership function, system status, linguistic variable, an indicator of quality, uncertainty, the superficial water, pollutant, ecological system, hazard class, maximum admissible concentration