The Impacts Of Urbanization And Agriculture On The Water Quality Of Huluka River, West Shoa Zone, Ethiopia

Abstract

Huluka River is one of the major surface water sources in the western Showa used by several hundred thousand of population in central Highlands of Ethiopia. However, numerous pollution sources exert significant pressure on the river. Different approaches for assessing the status of water quality were addressed. The aim of this study was to assess pollution effect of urban and agriculture by assessing fecal indicator bacteria (FIBs) and physicochemical parameters on the quality of Huluka River water. A total of 72 water samples were collected in three different seasons from December 2022 to August 2023 at 8 sites, where the river intersected forest (FA), agricultural (AA), agriculture-urban (Ag-Ur) and urban (UA) areas. For E. coli and Enterococci moderate to strong fecal pollution levels, ranging from 7.355 × 102 to 8.011 × 104 cfu/100 ml in CCA media and 8.92 × 10 2 to 9.41 × 104 cfu/100 ml in MEA media were observed, respectively. The lowest bacterial counts were noted in water samples collected in FA, and the highest in samples collected in UA. Statistical significance difference between the FIBs load within sampling seasons showed higher bacterial counts in rainy season than autumn and spring seasons (p= 0.002 for E. coli and p=0.000 for Enterococci < 0.05). On the other hand, onsite physicochemical parameter include: temperature, conductivity and pH were higher in the downstream course of the river whereas Dissolved oxygen was higher in the upstream sites. Dissolved oxygen, conductivity and pH were lower in summer season as temperature raised. Similarly, chemical parameters include total phosphorus and nitrate showed higher in the downstream sites especially in the urban area than other categories. Statistically, significance differences among sampling seasons were observed (p=0.000 for total phosphorus and p=0.000 for nitrate <0.05), hence both chemical parameters were higher in summer season than autumn and spring. Generally, the higher FIBs count and most of physicochemical parameter in the lower course of Huluka River except the lower oxygen saturation in the downstream impacted sites shows urbanization had more impact on the quality of Huluka River water.