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Public Water Supplies (PWSs) are managed by Irish Water, Ireland's national water utility, since 2013. Before this, public water supplies were managed by Local Authorities. More than 70% of public supplies take groundwater from boreholes, springs and infiltration galleries. This accounts for about 23% by volume (Irish Water, 2018).
Source Protection Areas (SPAs) are areas outlined around groundwater abstraction points (e.g. borehole or spring) which provide drinking water. The aim of the SPAs is to protect groundwater by placing tighter controls on activities within all or part of the zone of contribution (ZOC) of the source. The Zone of Contribution (ZOC) is the land area that contributes water to the well or spring.
Two Source Protection Areas (SPAs) are outlined. The Inner Protection Area (SI) aims to protect against the effects of human activities that might have an immediate effect on the source and, in particular, against microbial pollution. The Outer Protection Area (SO) covers the rest of the zone of contribution (ZOC) to the groundwater abstraction point.
Not all groundwater-fed public supply sources have SPAs outlined around them. Most studies (more than 125) have been carried out by the Geological Survey Ireland as part of County Groundwater Protection Schemes. The Environmental Protection Agency carried out more than 40 studies as part of the national groundwater monitoring network characterisation. Further studies have been carried out by consultancies for Local Authorities and Irish Water.
Different methods are used to map the entire Zone of Contribution to a spring, borehole or well, resulting in different degrees of confidence associated with the boundaries of the delineated area. To be able to specify the Inner Protection Zone within the entire Zone of Contribution, knowledge or estimates of groundwater travel time within the aquifer are needed (e.g. from site-specific hydrogeological parameters or tracer tests).
Source Protection Areas have been mapped by the GSI and EPA following the ‘GSI method’ (e.g., GSI/EPA/IGI Source Protection Zonation course, 2009; Kelly, 2010; DELG/EPA/GSI, 1999). These SPAs were mapped as part of County Groundwater Protection Schemes or as part of the WFD Groundwater Monitoring network characterisation. Other SPAs have been mapped by consultants for Local Authorities/Irish Water. They have not been peer-reviewed by the GSI.
The Zone of Contribution and the Source Protection Area account for the ‘horizontal’ movement of groundwater. Source Protection Zones are obtained by integrating the Source Protection Areas with the groundwater vulnerability categories. The Source Protection Zone includes the complete pathway, both vertical and horizontal, for re-charge and any entrained contaminants to the abstraction point.
Whereas the aim of delineating ZOCs is to define approximate areas that contribute water to an abstraction point, the aim of SPZs is to geo-scientifically characterise the pathway and receptor elements of risk to groundwater within the ZOC of a given source (Kelly, 2010). EPA prepared an advice note on “Source Protection and Catchment Management to protect Groundwater Supplies” that outlines the key measures and policies in place in Ireland (EPA, 2011).
This map shows the location of SPA's which have been mapped around public supplies of groundwater in Ireland.
This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.
It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas).
The data is shown as polygons. Each polygon holds information on Source Protection Area such as name, code, id, data source, county, reviewed by GSI and links to online reports
Group Water Schemes (GWSs) are community-run water supply schemes. About 70% of GWSs take their water from a privately-sourced supply. The rest take their water from an Irish Water connection (DHPLG, 2017). 81% of the privately-sourced supplies affiliated to the National Federation of Group Water Schemes (NFGWS) take groundwater from boreholes, springs and dug wells. This is around 54% by volume (NFGWS, 2018).
The NFGWS is the representative for community-owned rural water services in Ireland. The NFGWS assists schemes in meeting the challenges of water quality legislation and promotes a ‘multi-barrier approach’ to source protection. The ‘multi-barrier approach’ includes delineation of the Zone of Contribution to a supply source.
A Zone of Contribution (ZOC) is the land area that contributes water to a well or spring (Misstear et al., 2006). It can be considered as the ‘catchment’ to the supply source. Like surface water bodies, springs have natural catchment areas, whereas catchment areas to boreholes depend on a number of hydrogeological and meteorological factors plus the abstraction rate. A ZOC accounts for the ‘horizontal’ movement of groundwater and any entrained contamination once it has reached the water table and is moving towards the abstraction point.
The aim of delineating ZOCs is to define the area that contributes water to an abstraction point. Knowledge of where the water is coming from is critical when trying to interpret water quality data at the groundwater source. The ZOC also provides an area in which to focus further investigation and is an area where protective measures can be introduced to maintain or improve the quality of groundwater.
Different methods can be used to map the ZOC to a spring, borehole or dug well, resulting in different degrees of confidence associated with the boundaries of the de-lineated area. The ZOCs and accompanying reports should be considered as preliminary source protection studies. The work was undertaken by consultants under supervision and review by GSI, and represents a partnership between the GWSs, the NFGWS and GSI. The work was funded through the Rural Water Programme funding initiative of grants towards specific source protection works on GWSs (DECLG Circular L5/13 and Explanatory Memorandum).
The ZOCs were delineated in the period 2011 to 2019. The maps produced are based largely on the readily available information in the area, a field walkover survey, and on mapping techniques which use inferences and judgements based on experience at other sites. As such, the maps cannot claim to be definitively accurate across the whole area covered and should not be used as the sole basis for site-specific decisions, which will usually require the collection of additional site-specific data.
This map shows the location of ZOCs which have been mapped around GWS supplies of groundwater in Ireland.
This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.
It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas).
The data is shown as polygons. Each polygon holds information on name, year and consultant.