Precipitation and discharge during the storm of June 21, 2001.

During the storm of June 21, 2001, pH of storm discharge increased slightly but remained below 4. Specific Conductance (SpC) decreased with the onset of rain, but remained above 2 mS/cm, even when the discharge was at its maximum.

Precipitation and discharge during the storm of February 8, 2001.

During the storm of February 8, 2001, pH of storm discharge increased to about 6.5, and SpC decreased to less than 1 mS/cm. This was the last storm event that exhibited alkaline outflow with low concentrations of dissolved solids.

The passive anoxic limestone drain (PALD) that was installed to treat the discharge from the adjacent flooded underground mine is still producing an alkaline outflow, but its outflow is declining (possibly due to clogging), so the impact of an acidic seep that emanates from an adjacent area that was reclaimed in the past has increased over time. Although the pH of the streamflow is low, total acidities of the discharging waters tend to be less than 100 mg/L CaCO3 equivalent.