This book covers a diverse range of hydrogeological environments that occur in the Celtic regions of Britain and Ireland. These include hard rock aquifers of Lower Palaeozoic and Precambrian age, generally dominated by fracture flow within a shallow zone of weathering; Carboniferous Limestone aquifers, often characterized by conduit flows in karstic systems; dual-porosity Permo-Triassic sandstone aquifers; and Quaternary deposits, many of which form shallow granular aquifers. The papers presented here address a number of current issues common to the Celtic regions, including: groundwater protection policies, groundwater management in karst aquifers, groundwater development in Quaternary aquifers, groundwater evaluation in data-scarce aquifers and groundwater supplies to small island communities.