Bahir Dar city ’j surface water bodies are being influenced by different pollutions. Unavailability of waste water treatment plants and disposal of wastewater generated from different areas to lake Tana and Abay River are taking a big role in the contamination. This study explores the effects of waste water on the surface water bodies of Bahir Dar city by analyzing the characteristics of waste water. Primary and secondary data were used to carry out the research. Seven sample stations, of which five monitoring stations are connected to Lake Tana and two disposed to Abay River were selected for sampling. And the samples were taken once a month, for consecutive three months of the dry season and the wet season. The selected waste water parameters were E-conductivity, turbidity, Total dissolved Solids, Dissolved Oxygen, Nitrate, Biological oxygen demand , pH, phosphate and E-coliform. The samples were analyzed triplicates to obtain the average value. Analysis of variance– single factor was used to determine the seasonal variation of the parameters. Statistical Package for the Social Sciences, a twoway cluster was used to identify the highly polluted disposal points. The laboratory analysis indicated that all dissolved oxygen, Biological Oxygen Demand, and phosphate were above the maximum limits. Whereas, Conductivity, Total dissolved solids, turbidity, nitrate, most value pH and some E-coliform results are below the standard limits set by Ambient Environment standards for Ethiopian and Environment Protection Agency. The analysis of variance result indicates that all turbidity, most of the biological oxy gen demand, and nitrate of the samples didn’t have seasonal variation. While others parameters show significant differences at different seasons and sampling stations. SPSS results show the highly polluted waste water originates from cluster five which is dominated by cluster six . Generally, the surface water bodies are affected by the excess amount of dissolved oxygen, biological oxygen demand and phosphate. Key words: Bahir Dar city, wastewater, parameter, seasonal variation, surface water