Impact of parametric seasonal variations on water quality in the Crocodile River and Inyaka Dam in the Mpumalanga Province, South Africa

This study assessed seasonal variations in water quality and their impact on the Inyaka Dam and Crocodile River in Mpumalanga Province, South Africa. A total of 206 water samples were collected across four seasons to analyse parameters including pH, turbidity, electrical conductivity (EC), temperature, Manganese (Mn), Iron (Fe), phosphate (PO43−), nitrate-nitrogen (NO3-N), E. coli, total coliforms, faecal streptococci, and Bifidobacteria. Principal component analysis (PCA) and Pearson correlation identified major pollutants and their seasonal variations, while cluster analysis grouped water quality by parameter fluctuations. Findings indicated that water quality in both the Inyaka Dam and the Crocodile River exceeded permissible limits. In the Inyaka Dam, summer rainfall (202.68 mm) spurred microbial growth, including E. coli and Bifidobacteria, while winter saw elevated levels of PO43−, EC, Fe, and NO3-N. The Crocodile River exhibited its poorest water quality in summer, with high levels of conductivity, turbidity, Fe, Mn, and NO3-N, driven largely by rainfall. Winter pollution in the river was marked by E. coli, PO43−, total coliforms, NO3-N, and Bifidobacteria. The study highlights significant pollution in the Crocodile River, particularly in summer, linked to rainfall and effluent discharges. Microbial pollution persisted across seasons, influenced by both weather and point-source contamination. The winter season exacerbated water quality deterioration in the Crocodile River due to reduced flow, while Inyaka Dam's winter pollution was attributed to lake stratification. •Water quality worsens in summer due to rainfall and effluent discharges affecting both water resources.•The Inyaka Dam had peak parameter levels in winter caused by stratification within the dam.•Crocodile River's winter water quality declined due to reduced rainfall, leading to lower river flow.•Water quality management should be customised for lentic (Inyaka Dam) and lotic (Crocodile River) systems.