Assessment of Groundwater Quality and Hydrogeological Profiles within Odeda Local Government, Abeokuta, Southwest Nigeria

Groundwater quality can be affected by human activities such as agriculture and improper sewage disposal facilities currently in use by some homeowners within Odeda local government, Ogun State Nigeria. Sixty groundwatersamples collected from hand-dug wellswere analysed for physicochemical and bacteriological parameters using standard procedures. Results were integrated with multivariate and hydrogeochemical analyses to assess groundwater quality and hydrogeologycal facies within the study area. The range of values for the measured parameters include: pH (5.91 – 7.4), EC (101- 1142 μScm^-1), TDS (50 - 581 mg L^-1), NO_3 - (3 - 18 mg L^-1), Cl^- (25 – 234 mg L^-1), BOD (0.1 – 17.9) and E. Coli (ND - 45×10cfu mL^-1). The piper trilinear plot shows that the dominant hydrochemical facies in the study area is the Ca^2+– Cl^− type. A correlation analysis and a principal component analysis reflect dissolutions from basal rocks and contamination from biological wastes possibly arising from surrounding septic tanks or municipal waste disposal sites. There is need for a continuous monitoring of groundwater by relevant regulatory authorities to safeguard the human health and environment within the study area.