The discharge of untreated or inadequately treated tannery wastewater poses significant risks to both aquatic ecosystem and human health due to its toxic nature. The wastewater treatment plant at Bahir Dar Tannery Factory lacks tertiary and advanced treatment levels, which are essential for improved removal of nutrients and heavy metals. The plant emits a strong odor on its premises, and the wastewater appears highly turbid. Thus, the aim of this research was to evaluate the removal efficiency of the tannery wastewater treatment plant unit process. The research involved sampling wastewater at different stages of the treatment plant units during dry season (January to March, 2023) and wet season (July to August, 2023) and determination of chloride, sulfide, total dissolved solids (TDS), pH, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Phosphorus (TP), Total Nitrogen (TN), Total Suspended Solids (TSS) and total Chromium (Cr) and comparing the analysis results with national and international discharge limits. The performance limiting factors such as operation, cleaner practice and maintenance of treatment plant were assessed by preparing related questionnaires targeting engineering and administration department and by site visit. The results showed that chloride, sulfide, COD, TN, TSS, and Cr concentrations exceeded Ethiopian Environmental Protection Authority and World Bank group effluent discharge limits in both seasons. The final effluent qualities for TP and BOD, however, did not meet the international discharge standards but did meet the national ones. The overall removal efficiencies of the wastewater treatment plant for chloride, sulfide, TDS, BOD, COD, TN, TP, TSS, and total chromium were 48.77, 64.18, 15.97, 71.49, 57.36, 35.29, 16.68, 89.96, and 52.73 % during dry season and 48.85, 66.59, 18.41, 72.49, 57.08, 35.17, 23.75, 90.5 and 53.18 %, respectively in the wet season. According to respondents the plant operation, neither agreed that the tannery has an effective treatment plant operation system nor appropriate administrative structure, indicating that these factors negatively impact the plant's performance. In conclusion, making improvements to deal with the poor performance of wastewater treatment plant is necessary and doing so shall limit the effect of unsatisfactorily treated waste being discharged into the Abay River. It is advised to use odor-reducing chemicals, build an on-site lab, train workers, and maintain the treatment plant in order to handle the tannery's wastewater treatment problems. Keywords: Bahir Dar, performance, physiochemical, tannery, wastewater treatment plant