Dáil Éireann Debate, Thursday - 26 February 2026
316. Deputy Claire Kerrane asked the Minister for Public Expenditure, Infrastructure, Public Service Reform and Digitalisation when the Ordinary Summer Level (OSL) for Tarmonbarry Upper Lough was set; and if he will make a statement on the matter. [15991/26]
Amharc ar fhreagra318. Deputy Claire Kerrane asked the Minister for Public Expenditure, Infrastructure, Public Service Reform and Digitalisation where the minutes of meetings held daily/weekly to determine the amount of water to be released through Ardnacrusha and the Old River Shannon are available; the persons involved in these meetings; and if he will make a statement on the matter. [15993/26]
Amharc ar fhreagraI propose to take Questions Nos. 316 and 318 together.
Water levels on the River Shannon are managed by the ESB and Waterways Ireland. Information on the management of water levels is available at rivershannongroup.ie/management-of-water-levels/.
Water levels on the River Shannon are managed, to the greatest extent possible by those bodies, through the operation of gates and sluices at the outlets of the three major lakes and the operation of sluices and weirs at Jamestown, Roosky, Tarmonbarry and Meelick.
On a day to day basis, water levels on the Shannon are managed in accordance with agreed protocols between Waterways Ireland and the ESB. There is daily communication and a co-ordinated approach between those two bodies in this regard. Water levels on the Shannon are monitored on a daily basis, along with weather forecasts. This informs decisions around sluice opening and closing procedures and the operation of weirs, within the agreed protocols.
Tarmonbarry Upper Lough
Waterways Ireland has advised that the navigation depth upstream of Tarmonbarry Lough was calculated at the time of construction (circa 1840’s) based on the level on the upstream cill of the lock and allowing sufficient water depth upstream for vessels in the navigation channel.
Ardnacrusha
The ESB has advised that during normal operations all the water arriving at Parteen weir is passed through either Ardnacrusha station or down the old Shannon channel.
There is a minimum flow of 10m3/s through the old Shannon channel. All remaining water, arriving at Parteen Weir, up to a maximum of 400m3/s passes through the Ardnacrusha station.
When the amount of water arriving at Parteen Weir exceeds the maximum throughput of the Ardnacrusha station, excess water is passed through the old Shannon channel. The ESB has advised that this is only done when it is unavoidable and decisions are made daily by the ESB. .
This video ( youtu.be/AFhyeiraylkInformation ) illustrates how water flows through Ardnacrusha Station and Parteen Weir, while further information on levels and flows is published here esb.ie/what-we-do/generation-and-trading/hydrometric-information.
