Shannon water for Dublin

Some of the levels of understanding on this thread are worrying. Some of he numbers being thrown around are being selectivity or misguidedly used. As someone who looks at the published water levels on a weekly basis, using yearly average % figures is disingenuous at best.

This is an attempt to clarify some of the details and questions on this thread.

River Navigation.

Before the dam was built at Parteen, a few miles downriver from Ballina Killaloe, not Parteen village, there was a weir between where the Lakeside Hotel is and the bridge at Ballina. This kept enough water upstream for the river to be navigable. There is an entrance to the old Killaloe canal opposite the Lakeside Hotel. This canal used to go to O'Briensbridge. Below O'Briensbridge is the old erina canal which used to go to downstream of UL, allowing navigation to Limerick and beyond. During the 'Shannon Scheme' much of this infrastructure was removed or flooded, as the new reservoir and headrace canal took on these functions.

Sorry you've deduced that the 10m3/s isn't maintained by kayaking on it?

Of course the level on the old river changes through the year, it's a river. It's currently flowing per your link at circa 180m3/s because well it's Winter.

Iirc the flow into Lough Derg varies from 10 to 1000m3/s, so the 10m3/s maintained during the summer mirrors what would be flowing through it anyway if the reservoir wasn't there.

Suggesting that this will be turned off during a severe drought in favour of the pipeline is scaremongering, as there will always be enough water in the basin to supply both. It 'may' drop below normal operating level but we're talking inches here.

To clarify, my point about the massive difference in flows, is in relation to a % of annual water volume figure being used to justify a constant daily extraction figure.

To say that only 1.5% to 3% would be extracted daily is mixing 2 different data measures.

In winter flooding, the amount would be negligible. But during a reasonably dry summer it would be 15% to 30% of total water available, leaving the old river course far below the minimum current requirements, which themselves are deemed too low based on many of the studies done on the condition of the river and its supposed protected status.

There really was no need to build another massive reservoir when there's already a ready made one in existence.

Going forward with less reliance on hydrogeneration Ardnacrusha should become less important, so it's a no brainer to then use the existing basin for water supply.

One thing I'm minded of is thank God nimbyism wasn't around when the original project to electrify the country was enacted, we'd still be living in the dark, clearly those opposed to the pipeline still are.

Where do you think the water can be stored from the flooding time of the year until the middle of the summer? There isn't remotely enough capacity to store anything more than a couple of days at best in the Parteen basin. I was actually shocked when speaking to the engineer at one of the information nights about how little time the reserve of water would last and how long the current reserves for Dublin can last without needing replenishment. I would have expected it to be much longer.

In a dry summer the power station is practically unused, because there isn't enough water available to run that much water through it and the minimum requirement for the old river course has to be maintained.

John Rambo you have been hurling insults at people on this and the previous thread and now you admit to a familial self interest in exploiting the Shannon basin. How could anyone ever treat you as unbiased commentator now. You should have declared yourself long ago.

The gradient of the Shannon is less than you’d get on a train track, it’s an incredibly flat river. Ardnacrusha caused an ecological disaster when it was built and now produces so little power in the grand scheme of things that it should just be shut off to let the river recover.
The biggest reason the river sees flooding problems in winter and drought in summer is not the climate, it’s as a result of the massive drainage of the catchment by agriculture, BNM and the OPW.

If there was a proper scheme to re wet a good portion of the bog in the midlands and the poorer agricultural land as well as stopping all the pointless dredging (anyone with a decent understanding of how rivers behave will agree that dredging a waterway like the Shannon causes more harm than good), the benefits would be enormous.
There would be a restoration of the bogs to their proper state, a haven for wildlife, a carbon sink to rival the Amazon and a massive sponge to naturally regulate the flow in the river.
The proposed extraction rates wouldn’t be noticed even during droughts if the river was allowed to behave as it should.

That report contains some vague measures as assurances that the river would not be impacted.

no visible day to day difference and also stating that the operation of Lough Derg will feel and look very similar to the way it currently operates.

No 'visible' and 'very similar' are very subjective ways of stating something that surely should be measurable.

It also states that the amount of water extracted could be 5.34 m3/s when it is decided to extract 7 days worth of water in 5 days, which is part of the approval they are seeking.

It refers to a modelling effort that was done to compare the water levels and how they would have been impacted if the extraction had taken place. It would be interesting to see the full data set, as if it demonstrates that the river would not have been impacted even in the drought years with the proposed maximum extraction, then it would be a very effective tool to convince those against the project that it is not something that would need to be opposed.