The Physico-Chemical Water Quality of Streams and Channels Parameters of Streams Draining into Draining into River Rwizi, South Western Uganda

This study determined the physico-chemical parameters of streams draining into river Rwizi. Raw water was purposively selected from streams in the upstream, midstream and downstream sections of the river. There is a growth in the human population in the river Rwizi's catchment region, which is engaged in a variety of activities that have the potential to contaminate the river Rwizi, particularly along the streams. The physico-chemical condition of the main river Rwizi in Mbarara Municipality has been investigated. Water samples were collected in clean plastic bottles. Sample bottles were com- pletely filled and tightly secured. Water samples were analyzed within 5 hours from the time of collection and those not analyzed immediately were stored at 40C and warmed to room temperature before tests were carried out. The water samples were analyzed following the standard methods of American Public Health Association and standard operating manual (1985). The results showed that most of the streams in the downstream generally recorded the highest levels (p < 0.05) of the physico-chemical parameters followed by the mid- stream and lastly the upstream. Streams in the downstream recorded the highest levels in most of the parameters tested i.e. bus park stream (tempera ture, 27.60C; colour, 431.17 TCU; TSS, 99.33 mg/l; alkalinity, 468.33 mg/l; Mg, 121.89 mg/l; CaCO3, 588.67 mg/l; Cl, 333.33 mg/l), Kikutu stream (turbidity, 123.58 NTU; EC, 698 s/cm; DO, 55.73 mg/l; PO3+ , 12.85 mg/l), Kakyeka upper (pH, 10.52; NH+ , 46.67 mg/l), Rwentondo (Fe, 3.44 mg/l) and Kakyeka GBK (NO3, 10.83 mg/l). Most of the parameters downstream were higher than the EPA guideline (temperature, 250C; colour, 20 - 150 TCUs; TSS, 50 mg/l; alkalinity, 400 mg/l; Cl, 250 mg/l; DO, 5 mg/l;PO3+ , 0.5 - 0.7 mg/l; pH, 5.5 - 9.0; NH+ , 0.2 - 4 mg/l; Fe, 0.2 - 2.0 mg/l) and NEMA standards (colour, 300 TCUs; Mg, 100 mg/l; DO, 5mg/l; PO3+, 10 mg/l; pH, 6.0 - 8.0). On the other hand, the streams in the upstream registered the lowest values of the parameters i.e. Kibimba (temperature, 17.280C; EC, 31 s/cm; PO3+, 0.24 mg/l), Kasharara (colour, 15.17 TCU; TSS, 2.5 mg/l; pH, 6.23; al- kalinity, 19.67 mg/l; DO, 9.99 mg/l; Mg, 4.41 mg/l; CaCO3, 23.17 mg/l) and Karungu (turbidity, 7.02 mg/l; Fe, 0.12 mg/l). Water hardness in the streams ranged from soft to moderately soft (upstream), moderately soft (midstream), and moderately soft to abnormally hard (downstream) (downstream). The physico-chemical parameters fluctuated between high and low values without a clear seasonal pattern from March to May and June to August, indicating irregular weather patterns (i.e. fewer defined wet and dry seasons) during the study period, which could be linked to climate changes.