Physicochemical and Microbial Quality of the Asa River, Ilorin, Southwestern Nigeria

his study assessed the physicochemical and microbiological quality of water samples from a segment ofthe Asa River in Ilorin, Nigeria, over an eight-week period. Water samples were analysed using the multipletube fermentation technique and spread plate method, with microbial identification performed via standardmicrobiological procedures. Physicochemical parameters included pH (7.47–8.95), temperature (22.9–28.2°C),biological oxygen demand (BOD) (6.40–9.10 mg/L), total suspended solids, total dissolved solids, dissolvedoxygen, and total solids. Microbial analysis revealed total heterotrophic counts ranging from 2.70–7.25 × 104cfu/mL, total coliform counts from 1.45–6.05 × 104 cfu/mL, and faecal coliform counts from 1.45–3.40 × 104cfu/mL. Identified bacterial species included Streptococcus sp., Escherichia coli, Shigella sp., Pseudomonasaeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Vibrio cholerae. Antibiotic susceptibility testsagainst eight common antibiotics showed multiple resistance, particularly in Klebsiella pneumoniae. Fungalisolates included Aspergillus niger, Rhizopus stolonifer, Aspergillus fumigatus, and Penicillium sp. The pres-ence of antibiotic-resistant microorganisms indicates significant contamination of the Asa River, posing apublic health risk if used for domestic purposes.