Mr. Seán Laffey:

We have some limestone in the west but it is karstic in nature. It is prone to pollution because it is so open.

Surface water is also intimately linked to groundwater. For example, in the case of the River Slaney in Rathvilly, during the months of June, July, August and September, up to 75% of the water in the river is groundwater that emanates from the Wicklow hills, having been deposited during the winter.