Limerick City flooding: did ESB water management have a role here?

The Army has been drafted into Limerick to help battle “unprecedented” floods in the city. Scores of people have been evacuated from their homes across Limerick City after floods hit this morning. Large parts of the city and county are under water after the River Shannon burst its banks in several areas.

it needs to be asked if ESB’s recent management of water releases from Parteen Dam and Ardnacrusua had any significant impact on the flooding

The media have reported that high tides combined with strong winds caused the River Shannon to burst its banks at several locations. The River Mulkear was already in flood. However, the ESB were also spilling water from Parteen weir, and perhaps from Ardnacrusha. These issues all combined to cause this unprecedented flooding. According to the Irish Independent : ‘Worst flooding ever leads to evacuations‘. The limerick post has further information here, and also here.

Saint Mary’s Park in Limerick today

Saint Mary’s Park in Limerick today

When the floods recede it will be inevitable that water management protocols on the Lower River Shannon will be called into question again; and in particular it needs to be asked if ESB’s recent management of water releases from Parteen Dam and Ardnacrusua had any significant impact on the flooding? and if anything different could have been done to avoid this? The ESB stopped spilling water at Parteen last week abruptly returning discharge in the river from over 200 cumecs to a lower compensation flow; however significant quantities (again 200+ cumecs+) of water were being released today. If a steady high flow of water had been released at all times over the past week, would there have been available storage capacity in Lough Derg to capture the current flood flow temporarily and release it when the high tides and winds that battered Limerick had subsided? Would this have made a difference or not? – this serious question has to be asked.

The Old River Shannon today upstream of Limerick City. The ESB were spilling water here again today, despite having reducing flows to the base compensation flow earlier this week.

The Old River Shannon today upstream of Limerick City. The ESB were spilling water here again today, despite having reducing flows to the base compensation flow last week. Why is water not spilled continuously during wet weather to keep the river functioning as a more natural river, and reduce flood risk by restoring natural channel maintenance processes and increasing  the availability of emergency flood storage in Lough Derg?

This stop / start approach to winter water releases from Parteen Weir is certainly no good for the ecology of the Old River Shannon, as we have pointed out many times. But the real question that needs to be asked is did ESB’s water management over the past week increase flood risk in Limerick City due to using available storage capacity in Lough Derg to store water for hydroelectricity generation, rather than keep levels in the lake low to facilitate capturing and storing floods at key times; such as during the high tides in Limerick today that everyone knew were coming? Were they spilling water from Parteen and Ardnacrusha when these tides hit Limerick? 

old shannon

No water being spilled on the old River Shannon last week, after volumes (200 cumecs+) of water released were abruptly stopped by ESB and reduced to near compensation flow. This probably caused water levels to rise in Lough Derg, therefore reducing the potential to use Lough Derg for capturing floods. ESB builds up water levels in Lough Derg to allow water to be available for hydroelectricity generation on demand.

If ESB released water continuously at a higher and consistent level on the Old River Shannon over the winter, this would keep water levels on Lough Derg lower allowing for emergency storage during an event such as is happening currently. When the current mess is cleaned up, it is clear that an independent review of the approach of ESB to water management on the Old River Shannon is required.

Should the ESB have kept spilling water at Parteen Weir for the past week thus ensuring that there was excess available flood storage capacity in Lough Derg?

It is possible that nothing could have been done to stop the flooding, but there needs to be an enquiry about why, when tide and weather forecasts were so unfavourable, and when they were warned in advance by Limerick city councillors Diarmuid Scully and Michael Hourigan, did ESB stop spilling water at Parteen last week which may have reduced potential flood storage capacity in Lough Derg. Why were they spilling so much water today? The sudden drop in water levels on the Old River Shannon last week also caused significant ecological damage, as did the recent order of magnitude increases in flow. This all causes significant adverse effects in the Lower River Shannon Special Area of Conservation, designated for a number of water dependant conservation interests. Did it also contribute in any way to the flooding today in Limerick City?

We have recently called for a review of the Old River Shannon compensation flow in the context of an overall management plan for the Lower River Shannon.

Should the ESB have kept spilling water at Parteen Weir for the past week thus ensuring that there was excess available flood storage capacity in Lough Derg? They could then have tapered down flows released from Parteen Weir – and completely stopped generation at Ardnacusha – to coincide with the high tides. Water could have been allowed to build up in Lough Derg taking advantage of the storage that had accrued, and water releases could then have resumed when critical tide periods had passed.

It is possible that nothing could have been done, and we are not sure here that ESB did not do their best. This issue does needs to be investigated however. What is clear is that there are more sustainable ways to manage a waterbody like the Old River Shannon than the current approach being taken by the ESB. We have recently called for a review of the Old River Shannon compensation flow in the context of an overall management plan for the Lower River Shannon. Managing flood risk should come first as this is people’s lives and property that are being put at risk, and indeed destroyed today. Ecology and fisheries should be second, then the hydroelectricity generation requirements should be looked after. Current water management protocols on the River Shannon appear to put hydroelectricity generation first, and this will have to change.

Although not fully relevant to what has happened in Limerick, if you are interested in flood prevention as an issue you may also like this post I wrote recently about the need for more imaginative flood schemes. Click on this link to access this post.

One response to “Limerick City flooding: did ESB water management have a role here?

  1. Pingback: Call for a review of water management on the Lower River Shannon | Old River Shannon Research Group·

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