EFFECTS OF DREDGING ON DOWNSTREAM WATER QUALITY: EKOLE CREEK, NIGERIA

Water is essential part of ecosystem, so itsquality must be ascertainedfor use especially in Ekole creek of Nigeria where dredging activities is heavy, hence this study examined the dredging effect on the downstream water quality of Ekole creek. Water samples were collected from four points which are; Upstream, Dredge I, Dredge II, and Downstream points. The parameters of the water quality determined showed that Turbidity and Total Suspended Solids (TSS) were higher at the Downstream point with values of 31 NTU and 1664 mg/l respectively; pH was also sl ightly acidic (6.61); but low in Total Dissolve Solid (TDS), Electrical Conductivity, Nitrate (NO3) and Dissolved Oxygen (DO), as compare to the Upstream. The values of the heavy metals like Pb (3.845 mg/l), Cr (0.612 mg/l) Ni (0.104 mg/l) and Cu (0.128 mg/l), at Downstream point, were above Pb (3.0605 mg/l), Cr (0.0 mg/l), Ni (0.017 mg/l) and Cu (0.102 mg/l) of the Upstream point, before the Dredging points I and II, that have correlative matrix of(Pb>Fe>Mn>Zn>Cu>Ni>Cr) and Pb>Fe>Cr>Mn>Zn>Cu>Ni Downstream point. Is discovered the Downstream water is slightly acidic, high in Turbidity and TSS, but low in TDS, EC, NO3 and DO, as against the WHO drinking-water quality, due the effect of dredging on the water quality of the Ekole Creek. It is inferred that the dredging activities have negative effects on the water quality, which can be hazardous to the health of downstream user, and distort the ecosystem; therefore the commercial dredging activities should be checked in Ekole creek.