Monitoring and Assessment of Pollution-Induced Dissolved Oxygen Variation in River Challawa

The indiscriminate discharge of waste water effluents and municipal sewage into the river may impact
negatively on the health of aquatic organisms. The study is aimed at investigating the effect of industrial
effluents on the water quality of River Challawa. Chemical analyses of samples of the river water collected
at predetermined sampling points along a 10.644 km stretch were undertaken and the observations were
subjected to ANOVA and regression analyses.The results obtained indicated that the DO values ranged
from 2.4 mg/l to 1.9 mg/l, while the BOD5 ranged from 443 mg/l to 1654 mg/l; the COD ranged from 1296
mg/l to 4565 mg/l. The self-purification factor (f) for the River Challawa varies between 0.40 per day and
0.56 per day which puts the river in the sluggish stream category and as a heavily polluted stream.
Results showed that the incorporation of the variability of k2 in the determination of the oxygen sag
equation predicted values closer to the measured values than when it was ignored.The predictions
indicated significant relationship with the observed values at 95% level of significance.