Point and non-point source pollutions in developing countries are major surface water quality problems. In Ethiopia, Lake Tana's water quality has recently shown undesirable changes. Water pollutant loads from rural catchments were widely studied, but relatively little is known about pollution sources from urban. The objective of this study was to evaluate the water quality status of Lake Tana in the Gulf of Bahir Dar city. Physical and chemical water quality parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), nitrate (NO3), dissolved ammonium (NH4), phosphorus (DP), and heavy metals such as Chrome (Cr), copper (Cu), Iron (Fe), Zink (Zn) and manganese (Mn) were analyzed. The lake water samples were collected in the gulf area with reference samples outside the gulf in a dry season in March and a wet season in July and September. Water quality trend in the gulf was analyzed using literature available parameters. The results revealed that the pH resembled the alkaline range. Recorded concentrations varied from 0.08 to 2.85 mg/L for Cu, 0.10 to 1.60 mg/L for Fe, 0.04 to 0.22 mg/L for Cr, below the limit of detection (<LOD) to 0.07 mg/L for Zn and Mn was <LOD. The DP concentration ranged from 0.03 to 0.9 mg/L, N-NO3 ranged from 0.05 to 1.01 mg/L, and ammonia was only detected once. Concentrations of N-NO3 and DP surpassed recommended aquatic water quality criteria of the international guideline limit of the USEPA and WHO at all sites plus reference. Cr and Fe exceeded the criteria in severely polluted swage discharging areas from the hospital, marketplace, and lounges. The concentrations were also significantly high compared with the reference. The constituent's concentrations also showed different temporal variability. Cu and Fe concentrations were high in the dry period, but the rest parameters found low compared to the rainy season. The pollution trend of the lake in the gulf showed an increase. Therefore, comprehensive regulatory action and implementation of waste management are needed in urban for the ecological health of Lake Tana. Key words: Lake Tana, pollution, wastewater, urban runoff, heavy metals, nutrient