Аннотация
Due to geographical limitations (lack of natural receivers of treated wastewater) large sewage storage ponds are the main method of sewage disposal in the Republic of Kazakhstan. The paper presents the results of research on the environmental impact of sewage ponds serving the city of Kostanay (Kazakhstan). The scope of the research included the determination of basic quality parameters of raw and treated wastewater, the analysis of the chemical composition of groundwater in the vicinity of sewage ponds, and the analysis of the water quality of the Tobol River. The obtained results showed that efficiency of treatment facilities was unsatisfactory and water quality in the ponds did not meet requirements for surface waters for fishery. Highest contamination of groundwater was observed in sampling points close to the sewage ponds and was decreasing while the distance from the ponds was increasing. Multivariate analysis of the research data indicated that sewage from storage ponds, infiltrating into the ground, may affect quality of groundwater, which in turn supplying the Tobol River may also determine the quality of the river water.