Abstract

Assela, one of the developing towns in the south eastern central zone of Ethiopia, is located 175 km away from the Capital City of Addis Ababa. Anko River divides the town into two separate parts. In rural areas, water from Anko River is used for drinking and sanitation purposes. However, sewage from residential areas and Assela Hospital directly enters the river, affecting its quality. The objective was to determine Anko River water pollution status by the influence of wastewater discharge in Assela town. The cross sectional study design was conducted. The sampling techniques were wastewater samples taken from Assela Hospital waste water discharge site, upstream and downstream sites of Anko River for laboratory analysis in Addis Ababa. The average results of chemical and bacteriological parameters such as BOD₅ from 11.8 to 131.9 mg/L; COD from 115.7 to 206.2 mg/L, ammonia from 8.4 to 42.4 mg/L, nitrate varied from 1.6 to 3 mg/L, nitrite from 0.1 to 0.2 mg/L, and phosphate values varied from 2.1 to 6.3 mg/L, faecal coliform counts/100 ml varied from 180 to 600 and total coliform beyond WHO recommended for wastewater discharge. The correlations among the bacteriological and chemical properties were observed in the studied sites. Ammonia with phosphate, BOD₅ and COD had a significant positive correlation (r = 1.000, at P-value at 0.01, respectively). Nitrate had negative significant correlation with phosphate, BOD₅, COD and FCF(r = - 1 and -0.820, P-value < 0.01) and phosphate correlated with BOD₅, COD and FCF (r = 1 and 0.820, at P-value at 0.01, respectively). BOD₅ correlated with COD and FCF (r=1 and 0.820 with P-value at 0.001 respectively). Water borne diseases may be transmitted due to waste pollution of Anko River. Therefore, Assela town health departments have to take intervention measures on proper Anko River water treatment. Also, to reduce the faecal and total coliform organisms applying waste water treatment system with sand filtration followed by post chlorination systems must be recommended by Assela Hospital and municipality.

Key words: Water quality, indicator, water borne diseases, bacteriological and chemical water property.