Results of a systematic study on the water quality in the Moskva River and Oka River in western Russia are presented. The goal of the study was (1) to implement a water-quality survey concept, (2) to identify major pollutants and pollution sources, and (3) to study the influence of the Moskva River on the water quality in the Oka River. The results show that ammonium, phosphate, nitrate, AOX, and polycyclic aromatic hydrocarbons (PAH) are the major pollutants in both rivers. The Moskva River is significantly polluted. Concentrations of the pollutants exceed the corresponding water-quality targets by factors up to 14. The Oka River before the inflow of the Moskva River is fairly polluted. The water quality of the Oka River is strongly influenced by inputs of pollutants from the Moskva River. Longitudinal concentration profiles and multivariate data evaluation indicate insufficiently treated municipal wastewater from the Moscow area as the major pollution source in the studied river systems. With the results of the study, a basis for the effective implementation of measures for the improvement and protection of the water quality in the Moskva River and Oka River has been established.
