Spatio-Temporal Water Quality Assessment of Chhirapaani Reservoir, Chhattisgarh: A Chemistry Domain Study

Reservoirs are critical freshwater resources in central India, yet increasing pressures from agricultural runoff, domestic discharges, and seasonal variability threaten their long-term sustainability. The present study assesses the water quality of Chhirapaani Reservoir, Balrampur district, Chhattisgarh, with a focus on its suitability for drinking, irrigation, and fisheries. Nine representative sampling stations were selected across inlet, mid-reservoir, littoral, and outlet zones, and samples were collected in pre-monsoon, monsoon, and post-monsoon seasons. Physico-chemical parameters (pH, EC, TDS, DO, BOD, COD), major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, SO₄²⁻, HCO₃⁻), nutrients (NO₃⁻, PO₄³⁻, F⁻), and trace metals (Fe, Mn, Pb, Cd, Cr, As, Ni, Zn, Cu) were analyzed following APHA and BIS protocols. The Water Quality Index (WQI) indicated seasonal variation, classifying water as poor during pre-monsoon, medium in monsoon, and poor–medium post-monsoon. Heavy metals, especially Pb and Cd, exceeded permissible limits in localized sites, while nitrate and phosphate levels suggested risk of nutrient enrichment. Irrigation indices (SAR, %Na, RSC, PI, KR, MH) confirmed overall suitability for agriculture, though magnesium hazard values were marginally elevated in dry months.