Groundwater chloride response in the Highland Creek watershed due to road salt application: A re-assessment after 20 years

摘要: Summary Chloride from road salt enters streams primarily through surface runoff and groundwater discharge. Monitoring of dry-weather flow chloride concentrations in the Highland Creek watershed eastern Greater Toronto Area indicates presence a previously unrecognised, dual porosity aquifer system whereby preferential associated with “urban karst” exerts significant influence on baseflow early year. A mass balance undertaken annually over four successive salting seasons suggests that as much 40% applied shallow resulting net accumulation gradual increase mean concentrations. Assuming current application rates are continued, late summer will reach around 505 mg/L, almost double present levels. Elevated can affect potability water (the Canadian aesthetic drinking quality guideline for is 250 mg/L) also be toxic to aquatic organisms (CCME chronic toxicity 208 mg/L). Meeting these guidelines would require release salt-laden subsurface reduced by 50%.