The discharge of untreated municipal wastewater into surface water bodies is a major environmental concern, particularly in developing countries. Waste from industries, universities, and other institutions makes water a scarce resource. The objective of this study was, thus, assessing the impact of Bahir Dar municipal waste water discharges on the water quality of the upper Blue Nile River, Northwest Ethiopia. Wastewater samples were collected and analyzed for physio-chemical and biological qualities and heavy metal levels during both wet and dry seasons. The results showed that the dry season had a greater mean TDS value than the rainy season (848.66 and 702 mg/L, respectively). The mean values of pH (8.52 and 8.27, respectively) were nearly constant between the wet and dry seasons, and both were below the EHS limit. The mean electrical conductivity result was higher (1697.33 µS/cm) during the dry season than it was during the wet (1403.3 µS/cm), and both of them were above the WHO and ECS limits. During the dry season, the mean nitrate result was lower than during the wet season (22.75 and 28.2 mg/L, respectively), but during the wet season, the mean chloride result was higher (202.72 and 113.46 mg/L, respectively). Their respective results fell below of the WHO and ECS thresholds. The average TA result exceeded the WHO limit in both the dry and wet seasons, coming in at 211.66 and 66.67 mg/L, respectively. The average DO result was lower below the FAO, WHO, and USEPA standards in both the dry and rainy seasons, ranging from 3.33, and 1.29 mg/L, respectively. When compared to the rainy season, the mean phosphate and sulfate results were lower in the dry season (26.475 and 80.235; 38.65 and 57.138 mg/L, respectively). Sulfate, on the other hand, was below the WHO guideline while the phosphate result was above it. This study also included similar heavy metal (Cr, Mn, Fe, and Cu) analyses; however, the lead (Pb) concentration was always below the detection limit (ND) in all of the samples. Overall, the results indicate a strong correlation between the levels of total and fecal coliform for the bacteriological testing standard. Due to increased runoff and dispersion of pollutants, the wet season frequently shows higher levels of both FC and TC than the dry season. Therefore, the study concludes that the Bahir Dar Town Service Administration Office Authorities build and implement an integrated plan for handling municipal wastewater discharges to mitigate their adverse impact on the Upper Blue Nile River's water quality and ecological well-being.