Tag Archives: water level

The Black Bridge at Plassey

I am repeating here a point I made in response to a comment on this page. I do so because the point is, I think, an important one: some readers don’t check the comments and might miss this.

I have an imperfect copy [with some lines missing] of an indenture made on 8 July 1949 between the Minister for Finance and Limerick County Council under which the Council leased from the Minister

… all that those parts of the lands of Garraun and Sreelane on which Plassey Bridge abuts on both banks of the River Shannon and the site and piles of said Plassey Bridge together with said Plassey Bridge […].

I am not a lawyer, so my interpretation may be misleading, but I think that there are two points of interest.

The first is that, under the indenture, the Council is obliged to “well and sufficiently repair cleanse maintain amend and keep the hereby demised premises”, which includes the bridge. The Council is also required to “use the said demised premises as a public highway”.

The second is that, if the Council fails to do so, the Minister, and his agents the Commissioners of Public Works in Ireland, are entitled (after giving due notice) “to enter upon the hereby demised premises and to execute and to do the necessary repairs and works and the Lessees [ie Limerick Councy Council] shall repay the expenses of such repairs to the Lessor on demand […]“.

As far as I can see, Limerick County Council is in breach of its agreement with the Minister for Finance, and that Minister is entitled to repair the bridge and charge the Council for the cost.

If only there were a Minister for Finance who had an interest in Limerick (or in bridges) ….

A little rain goes a long way

Here are some water level readings from Athlone Weir. I’ve taken them from the OPW’s very useful water levels site, where you can monitor levels from the comfort of your own armchair. [If only there were a gauge at Killaloe ….]

At Athlone, staff gauge zero is 35.360m above Poolbeg datum (from 18 Oct 2003). I chopped the bottoms off the first two graphs. The first one shows the level for 35 days to 30 September 2014; I presume that the level of Lough Ree was being reduced to enable it to hold some of the autumn’s rainfall.

Athlone Weir 20140930

Athlone Weir 35 days to 30 September 2014 (truncated)

Here’s the graph for the 35 days to 15 October 2014.

Athlone Weir 20141015

Athlone Weir 35 days to 15 October 2014 (truncated)

Then, in October, the level began to rise again. By 30 October, it was back to about 2.1 metres, roughly the starting point on the first of the graphs above.

Athlone Weir 20141030

Athlone Weir 35 days ro 30 October 2014

And since then it has continued to rise.

Athlone Weir 20141117

Athlone Weir 35 days to 17 November 2014

Met Éireann’s weather summary for October 2014 [PDF] has this chart:

Met Eireann weather Oct 2014

Met Éireann rainfall October 2014

It says:

Rainfall: wet conditions nearly everywhere

Monthly rainfall totals were above-average nearly everywhere with the exception of stations in coastal areas in the Northwest and West and in parts of the Midlands. Percentage of Long-Term Average (LTA) values ranged from 81% at Gurteen to 161% at Johnstown Castle, which recorded it wettest October since 2002.

Fermoy (Moore Park) reported 135% of its LTA with 153.6 mm and its wettest October in 10 years. The wettest days were mainly the 3rd, 5th and 28th, with the month’s highest daily rainfall reported on the 5th at Cork Airport with 38.6 mm, its wettest October day in five years. Mullingar reported its wettest October day in 12 years on the 28th with 26.4 mm. The number of wet days (days with 1 mm or more rainfall) ranged from 12 at Casement Aerodrome to 24 at Valentia Observatory and Claremorris, with Claremorris reporting its highest number of October wet days since 1973.

Use of the OPW charts is licensed under Directive 2003/98/EC [PDF] of the European Parliament and of the Council on the re-use of public sector information. Met Éireann allows use of “the web pages, and the information contained within them, for private and non-commercial purposes, for teaching, and for research […] is allowed subject to the condition that the source of the information is always credited in connection with its use”.



Royal Canal water supply

On 26 November 2012 I noted that

The Royal Canal water supply applications have been approved by An Bord Pleanala. There were two separate applications […] but they were in effect treated as one.

There were conditions attached, but I concluded that

If I remember correctly, the amount of water available from Lough Ennell will not always provide enough (eg in a dry season) to keep the canal full. Still, this is a significant advance for Waterways Ireland and for Royal Canal enthusiasts.

So here we are, almost two years later, and the work of providing a supply from Lough Ennell to the Royal Canal, reckoned to be about a five-month job, has doubtless been long completed, no?


The work has not yet started and Waterways Ireland will be lucky if it gets done within the next year.

As I understand it — and if, Gentle Reader, you have more information, do please leave a Comment below (your name can be kept out of public view if you like) — there are three sources of delay:

  • first, I understand that there is a technical issue about one of the conditions attached to the approval; it is felt that the condition is unworkable, but that getting it changed might take some time. I presume it’s one of the conditions 2(a) to 2(d) that I quoted two years ago and, looking at the proposed orders published in the press [PDF], I suspect it might be the requirement to maintain the lake level at or above 79.325 mOD Malin Datum. However, I don’t really know
  • second, Waterways Ireland took over Clonsingle Weir, at the outlet from Lough Ennell, by Compulsory Purchase. Owners of mills, who generate electricity from the Brosna, have submitted claims for compensation. I understand that an arbitration hearing, lasting four days, is scheduled to be help in May 2015
  • third, responsibility for the scheme has moved from Westmeath County Council to Irish Water. Which may have other things on its mind.

Irish Water has published its proposed Capital Investment Programme [PDF] but Appendix 1, the Investment Plan Project Summary, is in a separate file [PDF]. Category B is headed Review Scope and Commence Construction and it includes

Mullingar Regional Water Supply Scheme (G) … Lough Ennell Abstraction.

I can’t work out what “(G)” means. A few items are so marked; a few others are marked “(H)”; most items have neither.

The Capital Investment Programme [CIP] document says:

 The CIP is dominated by contractual commitments entered into previously by Local Authorities, and which have now transitioned to Irish Water. In the 2014-2016 period, Irish Water will fund these contracts to completion and bring forward programmes and prioritised projects to commence. At the same time, it will progress a large portfolio of projects that are at the planning and design stage, reviewing their scope, budgets and, where appropriate, timing to favour maximising the performance of the existing assets through intensified capital maintenance that might allow deferral of major capital investment.

Emphasis mine. So that raises the possibility that Irish Water will decide not to fund the abstraction scheme but will rather opt to pay for continued pumping.

It is, of course, quite possible that I have misunderstood these difficult matters, so I will be glad to hear from anyone with better information.

Incidentally, reviewing Irish Water’s documents suggests to me that there are people there who know what they are doing and who have the expertise to manage large and complex operations. That differentiates them from the politicians in government and opposition, few of whom (as far as I can see) have any experience of running anything more complex than a parish social.




My attention was recently drawn to an article [PDF] by Mike Clarke about airholes.

The article is in Clogs and Gansey, the newsletter of the Leeds & Liverpool Canal Society, of which Mike is Founder and President. He is an extraordinarily knowledgeable person and it is well worth while looking around his website: for instance, there’s some material of Irish interest here, a list of publications here and material about the Leeds & Liverpool Canal here including a really excellent document about locks [PDF].

But back to the airholes.

Not being an engineer, or at all technically competent, I’m always reluctant to try explaining these mysteries, so I’ll welcome corrective Comments from any more technically-minded folk.

Water levels

If the water level on the upstream side of a lock gate is higher than that on the lower, the gate will be difficult to open. If the gate is the tail gate [bottom or lower gate] of a lock, you can raise a rack [paddle] and allow water to flow from the upstream side, which is the chamber of the lock, to the downstream side, thus making a level and allowing the gate to be opened easily.

If the gate is the breast gate [head or upper gate] of a lock, the same applies: you can lift a rack [paddle] in the upper gate, allowing the excess water to flow into the lock chamber.

However, the relationship between the heights of the two gates (or pairs of gates) then becomes important: if the breast gates are higher than the tail gates, the water level in the lock chamber will not be able to reach the height of the water above the lock (at least until you’ve drained down the entire level [pound] back to the next lock upstream).

But for efficient operation, you want to reduce the amount of adjustment that has to be done after the boat reaches the lock but before it can enter the lock chamber. You want a system that is, as far as possible, automatically self-adjusting. That means, in particular, one that ensures that the level of water above the lock is not too high.


On many English canals, that is done by using byewashes.

Byewash on the Huddersfield Narrow Canal (E) at Marsden

Byewash on the Huddersfield Narrow Canal (E) at Marsden

As far as I know, though, few Irish canal locks have them, and I have heard British boaters comment on their absence. If memory serves, the canal (Leitrim) end of the Shannon–Erne Waterway does, but I have no suitable photo. I should confess that I have no idea what proportion of Irish and English canal locks are so equipped; I will be glad if anyone who can supply, or point to, the information will leave a Comment below.


Mike Clarke’s PDF article, to which I pointed at the top of this page, provides a possible explanation for the absence of byewashes on Irish canals. He says that airholes were used instead on canals “built or influenced” by William Jessop. Jessop worked on the Grand Canal as assistant to John Smeaton from 1773 and was consultant engineer to the Grand Canal Company until 1802 [Ruth Delany The Grand Canal of Ireland David & Charles, Newton Abbot 1973].

Mike Clarke also says that Jessop trained John Killaly: Killaly joined the Grand Canal Company in 1794 and became its engineer in 1798 [Delany op cit]; furthermore, his designs were used on the Royal Canal from Coolnahay to the Shannon [Ruth Delany and Ian Bath Ireland’s Royal Canal 1789–2009 The Lilliput Press, Dublin 2010].

If I’ve understood Mike Clarke’s article correctly, the airhole system uses the channel for the ground paddle [land rack] sluice instead of building a separate byewash channel. From his photograph, I gather that there is a separate letterbox-like slot in the recess for the rack mechanism: I presume that excess water flows in through the slot, falls to the level of the sluice or channel from there to the lock chamber and thus flows into the chamber. If the tail [lower] gates are left open, or with one rack [paddle] lifted, the water can then flow out into the lower level.

Questions about Irish locks

Is my understanding correct?

What proportion of locks on each Irish waterway are equipped with airholes?

Are they still maintained and used?

Belmont Lock May 2009 IHAI 5_resize

Land rack [ground paddle] outlet, Belmont Lock, Grand Canal

Royal Lock 43 Killashee 18-02-2007 01_resize

Ground paddle [land rack] outlet, Lock 43 Killashee, Royal Canal

Royal Lock 6 02_resize

Possible inlet, Lock 6, Royal Canal

The next three photos were taken at Coolnahay, on the Royal Canal, during the period of very low water levels in 2012.

Coolnahay in drought April 2012 08_resize

Letterbox-like slot at Lock 26, Coolnahay, Royal Canal. I must look for similar features on Grand Canal locks and photograph them (if they exist)

Coolnahay in drought April 2012 19_resize

A second slot forward of the first (hidden by the land rack mechanism in the previous photo)

Land rack locked open at Lock 35_resize

Land rack mechanism locked slightly open: the slots were well above the water level at the time

It is of course entirely possible that all of this is so obvious that everybody else already knows all about it, but that I just didn’t understand what I was looking at. I read WI’s Heritage Survey of the Royal Canal [PDF], but it didn’t say anything about this sort of thing: or at least if it did I didn’t spot it. The report uses some non-standard terminology [eg “head gates”] so I may have missed its identification of the canal’s water-management features.

If, Gentle Reader, you know of the existence of papers or other published materials on these arcana, do please leave a Comment and, if possible, relevant links to online sources. It seems to me that there is a shortage of information about these technical matters as they apply to Irish waterways; it would also be nice if we were able to say which technologies were applied when to which waterways. I do not know whether, for example, we can assume that the lock gate designs in use today were always used on all Irish waterways.

Where do correct ideas come from?

Where do correct ideas come from? Do they drop from the skies? No. Are they innate in the mind? No. They come from social practice, and from it alone; they come from three kinds of social practice, the struggle for production, the class struggle and scientific experiment.

Readers will not, I am sure, need to be reminded that those are the words of the late Comrade Mao Tse-tung [or Mao Zedong, as the younger comrades say] in the Draft Decision of the Central Committee of the Chinese Communist Party on Certain Problems in Our Present Rural Work of May 1963.

Maurice Semple, in By the Corribside [self-published, 1981], lists writers who, from 1868 onwards, agreed with the view of the Cong Canal expressed by Sir William Wilde:

[…] for it was discovered, that like many other undertakings, the great canal at Cong “would not hold water.”

Those writers’ view is echoed by local people, and even by engineers, to the present day. Their case is, in effect, that the Board of Works engineers did not know what they were doing or did not properly survey the ground and were therefore surprised to find, on admitting water to the bed of the canal, that it vanished into sinkholes or swallow-holes in the karst.

One oddity about that belief is that the Cong Canal does actually hold water: it is full in winter, as the photos on this page, taken in February 2013, clearly show. It is empty in summer, but that is because water is unable to get in at the upper end, not (I suggest) because it flows out through the bottom.

What interests me at the moment is that I can find no evidence to support Wilde’s contention. Samuel Roberts, the engineer in charge of the work, knew that the work would be difficult but there is no hint in any of his annual reports that he feared that the difficulties might be insuperable. Furthermore, it is clear from his own reports and from other evidence that he was ordered to cease work on the navigation aspects of the canal before it was finished: there was never a moment when water was admitted to a completed navigation canal.

I have not been able to find any report from the 1850s in the Freeman’s Journal, the Cork Examiner, the Dublin Evening Mail or the Belfast News-Letter, or in any British newspaper, that supports William Wilde’s account of events. What, then, is its basis?

Of course my inability to find evidence does not mean that it doesn’t exist, but I would be grateful if anyone could point me towards it. I should say that I do not regard later accounts, like Wilde’s, as valid unless they include some evidence from 1854, the year of which Roberts wrote

The masonry in the Cong lock was commenced in March, and was progressing rapidly when I received instructions from the Board, in April, to suspend the execution of all navigation works in this division of the district, and complete only such as were necessary for the regulation of the waters of Lough Mask, for drainage purposes.

What I am looking for is an eyewitness, an official or some other reliable account, from 1854, that says “the canal was completed; water was let in; it vanished, to the surprise of the engineers”. If no such account exists, I may be forced to conclude that Wilde’s style of work is opposed to the fundamental spirit of Marxism-Leninism. As the Great Helmsman put it in the Little Red Book:

To behave like “a blindfolded man catching sparrows”, or “a blind man groping for fish”, to be crude and careless, to indulge in verbiage, to rest content with a smattering of knowledge — such is the extremely bad style of work that still exists among many comrades in our Party, a style utterly opposed to the fundamental spirit of Marxism-Leninism. Marx, Engels, Lenin and Stalin have taught us that it is necessary to study conditions conscientiously and to proceed from objective reality and not from subjective wishes; but many of our comrades act in direct violation of this truth.



The government’s new election manifesto construction strategy has just been published and can be downloaded here. I wouldn’t bother, though: there’s nothing in it about the Clones Sheugh and it’s written in the sort of turgid prose that won’t fry your brain: it will instead submerge your brain in a slurry pit and hold it under, providing a slow, choking, unpleasant death.

Anyway, the doughty Rob Kitchin has waded through it on our behalf and gives his conclusions here. I don’t share his enthusiasm for National Spatial Strategies and National Development Plans, but I have some sympathy for him when he says

I would have preferred something a bit more holistic, rather than trying to frame a whole bunch of stuff as a coordinated plan.

Michael Hennigan uses the B word.

Closing the Shannon in winter

I pointed out some time ago that, in the Dáil on 16 October 2013, Jimmy Deenihan said:

The [budgetary] provision will enable Waterways Ireland to deliver on its core activities and targets, which include keeping the waterways open for navigation during the main boating season and promoting increased use of the waterways resource for recreational purposes.

That was the first time I noticed the suggestion that, in effect, boating in winter might be de-emphasised, as it were; the idea is followed up in the current draft of the Waterways Ireland Corporate Plan 2014–6. The proposal receives some support from the figures for Shannon traffic in the first three months of 2014.

I realise that, as the numbers are small, they can be affected by the high water levels, bad weather or the date of Easter, but those for 2014 are remarkably low. The totals for the first three months [Jan–Mar] since 2003 are:

2003  689
2004  536
2005 2229
2006  683
2007  825
2008 1449
2009  687
2010  567
2011  626
2012  736
2013  753
2014  260

All the usual caveats apply, notably that the figures do not capture boating that is confined to the lakes. Still, the 2014 figure is less than half the next lowest, and it’s the first time since 2003 that the figure has been below 500, 400 or 300.


The Shannon in winter

Waterways Ireland has kindly supplied me with the Shannon traffic figures for January and February 2014. The usual caveats apply. I have not made any charts because the traffic levels were so low:

  • in January, nineteen boats were recorded; of them, ten went through Portumna Bridge. Thirteen boats were private and six hired
  • in February, thirteen boats were recorded, five of them at Portumna; nine were private and four hired.

The total of 32 boats in the two months is extremely low. Since 2003, the Jan–Feb totals have been:

2003   45
2004 112
2005  67
2006  92
2007 127
2008  72
2009 124
2010  72
2011 114
2012  94
2013  97
2014  32

As Waterways Ireland intends to “prioritise navigation opening times to the times of greatest use, in order to achieve maximum use of resources available”, we may expect the Shannon to be closed in winter.


The Gillogue railroad

Gillogue, in Co Clare, is the site of a former Burlington factory and of a Clare entrance to the University of Limerick. It is also the site of a lock on the Plassey–Errina Canal, a section of the old Limerick Navigation, and of quarries, gravel pits and lime kilns.

And, according to the 6″ Ordnance Survey map, of around 1840, Gillogue also had a railroad.

The Gillogue rail road

The Gillogue rail road (click to enlarge)

The railroad was almost certainly not for carrying passengers; it may have been a light railway, with small wagons pushed by men or pulled by horses, and designed to be taken up and moved elsewhere fairly easily. However, I have no hard information about who owned it, who built it or what it was for. I can make guesses, based on its closeness to the canal and to the quarries, but it would be nice to have evidence.

If, Gentle Reader, you know anything about it, do please leave a Comment below.

My OSI logo and permit number for website

Flood plains

Patrick O’Donovan [FG, Limerick] wants to drain the Shannon. Or wants farmers to do it. He doesn’t want the “multiplicity of agencies [which] have made it virtually impossible for anything to be done with the river and the rivers and streams draining into it”; he wants a non-multiplicity of agencies — “the OPW, the Department of the Environment, Community and Local Government, Inland Fisheries Ireland or whoever” — to dig sheughs and stop flood plains flooding. He says

The one group of people who seem to have no say are those who live on the banks of the rivers or who have watched thousands of gallons of water coming in their front door and out their back door.

But he is wrong. That is the one group of people who can stop flood waters coursing through their houses and who can do it most quickly, most easily and without the permission of a single state agency.

The solution is simple: they should move house, away from the flood plains to higher ground.