The intensive inflow of pollutants into ecosystems necessitates the development of a methodology for assessing the state of ecosystem reliability in order to implement measures aimed at ensuring their environmental sustainability. The paper studies the distribution and redistribution of anthropogenic pollutants in hydroecosystems. The reaction of living organisms to the impact of pollutants is determined using the method of mathematical modelling. Changes in the self-regulation mechanism are described on the example of interconnected components of the Dnipro basin system: «small river - medium river - large river». It has been established that the constant trophic connections between the rivers of the Dnipro basin provide a homeostatic mechanism for the development of a single integrated basin system at different levels of hierarchical development. The obtained results allow us to consider the complex system of the basin as a set of hierarchical structures united by hydrographic interconnections and functionally.
