Assessment of surface water receiving sewage effluents for gardening irrigation purposes: a case study of Ona River in Ibadan southwest local government area of Oyo State, Nigeria

The analysis of chemical quality of Ona River in Ibadan Southwest Local Government (IBSWLG) area of Oyo State was undertaken in this study to assess its suitability for irrigation purposes by considering two major seasons in the ecological zone. In order to achieve the said objectives, fourty sampling points were selected along the stream at about 20m interval. The water samples collected were analyzed in the laboratory using methods of Ademoroti (1996). The result showed that despite the large content of sewage effluents characterized by some of the areas, the quality of the surface water remains within the safe limit for irrigation purposes; thus, Ona River water can be developed for all-year round crop production in the study area. However, the need to continuously monitor and assess surface water quality for irrigation is stressed.