Organic, nutrient and hazardous surface water pollution is mainly caused by direct or indirect discharges of insufficiently treated wastewater from sewage treatment plants. Thus, the present study highlights the degree of pollution of the Răut River, downstream from the upstream by the wastewater treatment plant from Bălți city (WTP Bălți), from the physic-chemical point of view of surface water quality. In the Republic of Moldova, the quality of wastewater discharged into natural receivers is regulated by Government Decision no. 950 of 25.11.2013, regarding the requirements for the collection, treatment and evacuation of waste water in the sewage system and / or in natural water bodies for cities and rural towns. Therefore, in the first quarter of 2023, water samples were taken from the Răut river, upstream and downstream of the wastewater discharge from WTP Bălți. The determination of the physic-chemical quality parameters of the surface water in the water samples was carried out in the accredited laboratory "Laboratorul Investigații de Mediu" S.R.L., by me personally. According to the results of laboratory tests, a high degree of pollution with organic substances was found: COD (upstream 67.7 mg/l; downstream 103.5); BOD5 (upstream 16.9 mg/l; downstream 25.9); N/NH4+ (upstream 1.63 mg/l; downstream 18.1 mg/l); Ptot (upstream 0.55 mg/l; downstream 1.70 mg/l). There is an obvious pressure on the quality of the Răut river, downstream of the wastewater discharge from WTP Bălți, due to the reduced effectiveness of the biological step, the bacteria and microorganisms (activated sludge) in the aeration basins are not able to degrade the organic substances. Thus, insufficiently purified water is discharged directly into the Răut river. Due to the small flow of the river, the process of self-purification of surface water stagnates. In conclusion, wastewater treatment is of colossal importance for the protection and maintenance of the environment in the best conditions. The image of the polluted Republic of Moldova should become a thing of the past, so legal regulations and European standards must be respected, active participation in the treatment and cleaning of wastewater in order to achieve a sustainable management of aquatic resources.