During the spring of 1985 shallow recharge area groundwaters at depths less than one metre in the Turkey Lakes watershed were observed to undergo short term (1 to 10 days) pH and alkalinity depressions associated with both rain and snow melt events. At the same time the concentrations of K+ in the groundwater increased. Observations suggest that, if, during an individual loading event, the loading rate of Hydrogen ions (H+) exceeds the rate at which alkalinity is made available through carbonate weathering reactions, increased alumino-silicate alteration can occur. Thus alumino-silicate alteration may occur in groundwater systems with measurable carbonate alkalinity.