By comparison with the Grand Canal, which had about fourteen feeders supplying the main line, the Royal seems to be almost a desert: I have found only five supplies. That may be because less has been published about its water supply, which receives comparatively little attention in either Peter Clarke’s The Royal Canal: the complete story (Elo Publications, Dublin 1992) or Ruth Delany and Ian Bath Ireland’s Royal Canal 1789–2009 (Lilliput Press, Dublin 2010). Furthermore, I have no map equivalent to that which I used for the Grand Canal, which was useful in naming the feeders.
Most attention has focused on the Lough Owel feeder, which supplies the summit level, but it was not (and is not) the only source of water. Here is a list assembled from personal observation and from the OSI maps of ~1840 and ~1900, the Guide to the Royal Canal of Ireland (compiled by Ruth Delany and Ian Bath and published by the Office of Public Works in 1994) and some information from Waterways Ireland.
The OSI surveyors working along the Royal seem to have been less interested in canal feeders, or perhaps there just weren’t as many. In several places they seem to have marked feeders with the letters CS rather than the words Canal Supply, making them rather harder to spot. As a result, I am not confident that this list is comprehensive and I would welcome additions, corrections and clarifications; please leave a Comment below.
Again, the list goes from east (Dublin) to west (the Shannon).
There is more about the Lough Owel Feeder here.
Is that all there is? Comments particularly from folk who’ve been along the Royal recently.
Update November 2012
The Inspector’s Report to An Bord Pleanála on the Royal Canal Water Supply Scheme PL 25.JA0030 and PL 25.PW3005 reports that Nigel Russell, WI’s Director of Technical Services, described the “sources of water to the canal”:
Apart from the summit Mr Russell noted that around Enfield there is some natural inflow as the canal is in cutting. There are two small gravity feeders in addition, the Thomastown feeder, a small stream, and the Rye water, which operate in flood weather conditions. The Boyne and Inny have been pumped over the last ten years and in times of low flow have been a significant source of water. In low flow the only Lough Owel derived water is from the fish farm. If it is considered that pristine Lough Owel water is the main source of water to the canal that is not accurate. Lough Owel supplies the canal during high water levels. At low flow times the canal sources are pumped water from the Boyne and Inny, Lough Owel water and Cullion fish farm recirculated water. […] Mr Russell indicated that the relative contributions of water at times of low flow could not be estimated. Losses of water through seepage is being addressed and illegal abstractions are being pursued. A large throughput of boats will give rise to large losses.
Update November 2018
Waterways Ireland is still pumping from the Inny into the Royal Canal at the Whitworth Aqueduct, north of Abbeyshrule, but the level is still well below normal.