Datasets of hydro energy generators connected to the electricity network are downloadable as GIS shapefiles. Two spatial reference systems are applied to the downloadable shapefiles: Irish Transverse Mercator (ITM) and WGS 84 (EPSG:3857).

Connected generators are those with an electrical connection to the electricity network or “grid”. Each connection is quantified by a Maximum Export Capacity (MEC), expressed in megawatts (MW). Hydro generators built over multiple phases appear in these datasets as individual generators, each with a total MEC value. Such generators are larger, TSO-connected, and built in early decades of the State at: Ardnacrusha, Cliff, Cathleen’s Fall, Inniscarra, and Pollaphuca.

The Sustainable Energy Authority of Ireland (SEAI) offers the same data in its Hydro Mapping System, a digital map of Ireland's hydro energy connections and resources (http://gis.seai.ie/hydro).

References
Ireland’s Distributed System Operator (DSO) and Transmission System Operator (TSO), ESB Networks and EirGrid respectively, provided the raw data on hydro energy connections. They publish their datasets, for information purposes, at:

DSO Connected-Energised Non-Wind Generators (ESB Networks)
https://www.esbnetworks.ie/new-connections/generator-connections-group/generator-statistics

TSO Connected Renewable Generators (EirGrid Group)
https://www.eirgridgroup.com/customer-and-industry/general-customer-information/connected-and-contracted-generators/