Abstract:

The mean dissolved oxygen (DO) concentrations at Kalange-Makwanzi and Buyala Kikubamutwe were comparable over the monitoring period, with the upstream transect consistently having lower dissolved oxygen compared to the downstream transect but showing concentrations of over 5 mg/L in both transects. Thus, the concentration of dissolved oxygen was consistently above the minimum (3 mg/L) that is required for survival of most aquatic biota especially fish. The mean pH at both transects was circumneutral and comparable to that of Lake Victoria and is within the NEMA prescribed range of 6 to 8. The slightly lower temperatures compared to the previous data were probably due to the cooling effect of the rainy season and was within the permissible NEMA range of 20 to 35°C. Other than conductivity, temperature and pH conditions were within ranges that have been recorded from Lake Victoria waters (NaFIRRI - IFMP 2007 and 2008), and conform to national effluent discharge standards set by the NEMA. Water clarity reduced at the downstream transect compared to the upstream one, but was comparable to previous readings. Less suspended solids were recorded in the waters at both transects compared to what was noted in April 2009, and were below the NEMA standard of 100 mg/L. Current observations showed a more than 6-fold concentration of oil and grease in the downstream compared to the upstream transect but, the concentration was still below the NEMA upper limit of 10 mg/L.