Abstract

The research aimed to evaluate the current wáter quality of Lake Hawassa in order to identify potential pollution sources and suggest appropriate measures. Physico-chemical water quality parameters have been determined by taking duplicate samples from seven sampling sites and the results were compared with WHO and FAO standards. The findings of the study revealed that the concentration of metals such as manganese (0.83 mg/L), zinc (5.75 mg/L), chromium (0.22 mg/L), phosphate (1.31 mg/L), and biochemical oxygen demand 5 (BOD5, 68.7 mg/L) exceeded WHO standard that could be due to point sources pollution from ceramics, textile, plastics, leather tanning and food processing industries located near the rivers and streams that end up into the lake. Moreover, the study indicated that the lake has also been polluted by non-point source pollution caused by urban stormwater, agricultural runoff, over grazing, deforestation, soil erosion and land development as it was shown with elevated levels of total dissolved solids (TDS, 928.3 mg/L), electrical conductivity (EC, 1851.4 μS/cm), turbidity (47.9 NTUs), fluoride (15.3 mg/L) and potassium (74.2 mg/L). Therefore, intervention measures should be put in place to prevent pollution of the lake.

Key words: Ethiopian Rift Valley Lakes, surface water pollution, water quality parameters, nutrients, metals.