Water Quality Assessment of the Bontanga Reservoir.

Abstract

The water quality assessment of Bontanga reservoir in Northern Region of Ghana has been carried out and results obtained were based on samples collected from three sampling points monitored over a period of four years. Many of the parameters analysed were within the World Health Organisation’s (2008) permissible levels for drinking water, and the Ghana Water Resources Commission target raw water quality range for domestic water use, with an exception of microbiological quality. The physico-chemical parameters ranged from 6.77 to 8.52 (pH unit), 0.43 to 39.40 NTU (turbidity),  2.50 to 30.00 colour units (colour), 44.50 to 135.00µS/cm (electrical conductivity), 24.20 to 39.10 mg/l (total dissolved solids), 20.00 to 88.00 mg/l (total hardness), and dissolved oxygen levels of 9.32 to 10.36mg/l. The mean concentration of sulphate in the dry season was 4.33mg/l and 8.07mg/l in the wet season. Nitrate-N and phosphate ranged from 0.01 to 4.00mg/l and 0.015 to 0.024mg/l respectively. The heavy metals concentration ranged from 0.017 to 0.025mg/l (Cu); 0.15mg/l to 0.20mg/l (Fe), 0.01 to 0.03mg/l(Cr),  0.12 to 0.21mg/l(Mn), 0.010 to 0.014mg/l(Pb), 0.001 to 0.227mg/l (As) and 0.002 to 0.003 mg/l for Cd. The silica ranged 4.70mg/l to 23.90mg/l (SiO₂). Total coliform counts ranged from 3,500 to 15,000 cfc/100ml with an overall mean of 9,250 cfc/100ml. The reservoir exhibited an overall ionic dominance pattern of Na > K > Ca > Mg and SO₄ > HCO₃ > Cl.

Keywords: Bontanga Reservoir, Water quality, Physico-chemical analysis, Microbial analysis.