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Physicochemical and Microbiological Quality of Surface Water and Groundwater during Wet and Dry Seasons in the Fétoré Sub-basin, Guinea



Author(s)

Alpha Oumar Diallo¹, Elhadji Thierno Doumbia^1,2, Fousseini Kouyate¹, Michael Dieng¹, Binta Sombily Diallo¹ and Mamadou Kabirou Bah¹

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DOI:10.17265/2161-6213/2026.4-6.003

1. Laboratoire Écologie et Sciences de l’Environnement, Institute of Research in Environment of Guinea (IREG), Gamal Abdel Nasser University of Conakry, BP 1147, Conakry, Guinea
2. Laboratory of Atmospheric Physics and Oceanography-Simeon Fongang (LPAO-SF), Polytechnic High School, Cheikh Anta Diop University of Dakar, BP 5085, Dakar, Senegal

Water quality in the Fétoré sub-basin, a tributary of the Konkouré River in Guinea, was assessed during the wet and dry seasons of 2024. Surface water and groundwater samples were analyzed for physicochemical parameters and fecal indicator bacteria. Surface waters were generally weakly mineralized, with mean conductivity of 73.1 µS/cm in the wet season and 85.6 µS/cm in the dry season, while dissolved oxygen remained relatively stable at 6.06 and 5.81 mg/L, respectively. Several parameters showed marked spatial and seasonal variability. Mean nitrate concentration increased from 6.45 mg/L in the wet season to 21.71 mg/L in the dry season, with a maximum of 110 mg/L. High local values were also recorded for turbidity (55.5 NTU), TSS (total suspended solids) (62 mg/L), BOD5 (biochemical oxygen demand over five days) (21 mg/L) and COD (chemical oxygen demand) (45 mg/L). Microbiological contamination was widespread in surface waters. Total coliforms were detected in 100% of wet-season samples and 85.7% of dry-season samples, while fecal coliforms were detected in 93.3% and 71.4%, respectively. Maximum concentrations reached 112 CFU/100 mL for total coliforms, 95 CFU/100 mL for fecal coliforms and 175 CFU/100 mL for fecal streptococci. Groundwater showed lower microbial contamination and generally lower turbidity, but phosphate concentrations remained high, ranging from 5.3 to 14.1 mg/L. Fecal indicators were nevertheless detected in groundwater during the wet season, with positive detections reaching 25% for total and fecal coliforms and 75% for fecal streptococci. These results show strong spatial and seasonal contrasts in water quality across the Fétoré sub-basin and identify localized physicochemical and microbiological contamination. They support the need for regular monitoring of both surface water and groundwater, particularly where these resources are used for domestic purposes.

Fétoré sub-basin, water quality, hydrochemistry, microbiological contamination, seasonal variability, Fouta Djallon, Guinea.