Using electrical conductivity to predict sulfate levels in livestock drinking water in Saskatchewan

This study investigated the factors affecting water sulfate levels and explored the use of electrical conductivity (EC) in predicting high sulfate water using 3491 water quality records. A cut-off value of 2500 mg/L of water sulfate levels was used to differentiate safe and unsafe water for livestock. The predictive accuracy of three EC cutoff values, 4000, 4250, and 4500 µS/cm, were determined and compared to identify the best cutoff value. Approximately 10% of water contained unsafe sulfate concentrations, while well and spring had the best quality water. The highest sulfate level was registered in 2021 when there was pronounced drought in the region. While season did not affect sulfate levels, sulfate-to-total dissolved solid (TDS) ratio did differ ( p < 0.05) with high ratios observed in spring and summer. The 4250 µS/cm EC cutoff value had the best performance metrics and could be used with high confidence in diagnosing water safety in terms of sulfate concentration. However, because the diagnostic potential of electrical conductivity depends on the stability of the sulfate-to-TDS ratio, periodic laboratory testing of water should be encouraged to verify that this EC cutoff remains highly predictive of safe water.