International Science Community Association International Research Journal of Environmental Sciences 15 3 2026 07 22 Seasonal and Spatial assessment of Physico-chemical and Microbiological water quality of the Sohiong River, Meghalaya, India 1 9 EN Thabah Marshal 1 Department of Environmental Science, Shillong College Meghalaya–793115, India Thabah Hubertwell 2 Department of Environmental Science, Shillong College Meghalaya–793115, India Nongbri Batriti 3 Department of Environmental Science, Shillong College Meghalaya–793115, India > Research Paper 2026 3 27 2026 07 22 The current study analyzes the Sohiong River's physico-chemical and microbiological quality in the East Khasi Hills District of Meghalaya, as well as its seasonal and geographical variations. Water samples were collected from upstream, midstream, and downstream areas during the rainy and dry seasons. Standard laboratory methods were employed to analyze the parameters of pH, temperature, electrical conductivity, hardness, alkalinity, chloride, sulphate, nitrate, phosphate, biological oxygen demand (BOD), and total coliform. Descriptive statistical analysis, correlation analysis, and Water Quality Index (WQI) were used to interpret the results. The data obtained from the study show that most of the physicochemical parameters were found to be within acceptable limits in both seasons, with relatively stable pH (6.49-7.25), temperature, and conductivity. Descriptive statistics showed that the parameters had low spatial variability for pH, temperature, conductivity, and BOD, but high variability for sulphate, chloride, and total coliform. Pearson correlation analysis showed that there were significant relationships between various parameters, indicating the effect of seasonal hydrological conditions on nutrient and ionic cycles. The river water quality was good to exceptional during both the wet and dry seasons, with somewhat higher values during the dry season, according to the estimated WQI. However, total coliform levels were found to be as high as 1600 MPN/100mL in some places, despite the favorable physicochemical conditions, indicating microbiological contamination. In general, the study proves that although the Sohiong River has good physico-chemical water quality, microbial pollution is still a concern, emphasizing the need of regular monitoring and remediation strategies. Copyright@ International Science Community Association