Evaluation of Some Groundwater Sources in Ota, Ogun State, Southwestern Nigeria

In a three year study (2018, 2019 and 2020), some groundwater sources in Ota, Ogun State, Nigeria were evaluated for quality. A total of one hundred and eighty composite borehole water samples were collected from 10 locations/sites in the study area. The sampling sites in the study were A (Iju), B (Onipannu), C (Ilogbo), D (Arobieye), E (Igbooloye, F (Osi), G (Ijoko), H (Akeja), I (Oju-ore) and J (Iyesi). Samples collected were analyzed using standard procedure for pH, electrical conductivity (EC), total dissolved solids (TDS), chloride and iron (Fe). Results over three years showed that the water was acidic with pH < 6.5, EC ranged from 39.52±0.79 to 134.99±0.03 µS/cm, TDS ranged from 19.43±0.42 to 81.00±0.02 mg/L, chloride was consistent at 0.02±0.00 mg/L while Fe ranged from 0.00±0.00 to 0.11±0.08 mg/L. There was no definite yearly trend except for Fe which dropped from 0.036 mg/L in 2018 to 0.011 mg/L in 2020. Modelling the data for consumption using water quality index (WQI) showed that the groundwater is of excellent quality with WQI < 50 while for health risks using the average daily dose (ADD) and hazard quotient showed that the groundwater would pose no non-carcinogenic risks. Periodic monitoring covering more parameter is recommended to reflect the proper status of groundwater sources in Ota.