Water monitoring stations used by the EPA and Local Authorities are registered on EDEN Monitoring Data System by an application called the Feature Coding Tool (FCT). This tool applies a unique code to river, lake, transitional, coastal or groundwater stations registered on it.
More information from the EPA at:
https://www.epa.ie/our-services/monitoring--assessment/freshwater--marine/water-monitoring-and-assessment-/
and
https://gis.epa.ie/EPAMaps/Water