The ESB and Ardnacrusha


Sir, – Seamus Fennessy (January 6th) asks, “Why are we storing winter rains in a river that is low lying and prone to serious flooding?” The ESB does not store winter rains on the Shannon or in any of its lakes.

The level in Lough Derg is maintained within a narrow band of 0.3m in order to flow water into Ardnacrusha. The capacity of Lough Derg within this band equates to less than half a day’s inflow from the Shannon at the current flowrates, in the context of a flood that has been going on for over a month.

The ESB adjusts Parteen Weir below Lough Derg to divert the maximum possible flow of water away from the Shannon and into Ardnacrusha, before channelling that water back into the river at a point downstream on the outskirts of Limerick City.

Although I know that it will be of little comfort to those families whose properties and lives have been so badly affected by the current level of flooding, almost half the water flowing down the Shannon during the recent period of heavy and persistent rainfall has been diverted by ESB away from the vulnerable areas that lie immediately downstream of Parteen Weir.

So the issue of ESB storing winter rains for summer electricity generation or, for that matter, storing any water on the Shannon does not arise. Indeed, the existence of Ardnacrusha is positive and beneficial in a flood and its absence or decommissioning would only exacerbate the current difficult flooding situation downstream of Parteen Weir.– Yours, etc,


Corporate Communications

& Public Affairs,


Lower Fitzwilliam Street

Dublin 2.