The article describes modern anthropogenic load on the surface water of the Southern Bug River Basin in a changing climate. The main water users-pollutants of the Southern Bug River Basin in Vinnytska and Mykolaivska regions were identified. The water quality of the surface water of the Southern Bug River in time and space (along the river stream) was analyzed. The water quality of the Southern Bug River was assessed by complex indices for different water users. In order to assess water quality, it is recommended to use complex indices that take into account the effect of the total action of pollutants. The self-purification potential and capability of restoration in space (along the river stream) of the aquatic ecosystem of the Southern Bug River was established for 2019. The results of the study allow us to state that the use of surface water of the Southern Bug River Basin for drinking, fishery, cultural and recreational needs is related to certain environmental risks. It is recommended to carry out the environmental protection measures aimed at adjusting the priorities of economic activity, reduction of wastewater discharge and increase in the water content of the river by regulating the operation of energy complexes.