Walking our engineering landmarks: Parteen Weir

By The Helpful Engineer / On / In Historic Buildings

Parteen WeirPeople go walking for lots of reasons. But what about combining a walk with some of our engineering heritage? Its easy to do. Just look up a few interesting engineering landmarks on the net, find them on Google Earth and see if there is a safe walking route nearby. I did this a while ago and visited Parteen weir on the River Shannon.

The Shannon Hydro Electic Scheme. Parteen Weir forms part of the Shannon Hydro Electric Scheme. When constructed in 1924, the Shannon hydro project, was the largest hydro electric project in the World. The electricity generated at the time was sufficient to supply the whole of Ireland. Read more about the scheme here and here.

The main parts of the Shannon Hydro Scheme are:

  • Parteen Weir. This controls the flow of water being directed to the dam. Dividing the flow of the river between that directed towards the dam and that directs along the original route of the river.
  • The headrace canal. This 14km man made canal flows from the weir to the dam.
  • Ardnacrusha Dam. This is where the electricity is generated. It uses the water in the head race canal, and the 29m height difference between the weir and the dam to drive five large turbines to generate electricity. It also contains a lock for smallish boats and a rather inefficient fish pass. See Irish Waterways History for a fascinating description of navigating this lock in a boat.

Walk to Parteen Weir. There is a lovely loop walk along the River Shannon from the public car park in O’Briensbridge in County Clare to Parteen Weir. The weir itself is exciting with the noise and energy of all the water crashing through it. Especially considering that the water actually falling through is only a small fraction of the rivers flow. The vast majority of the flow bypasses the weir.

After viewing the weir you can retrace your steps back along the river or create a loop walk by walking back to O’Briensbridge via the head race canal. As stated above the function of the weir is to control the water flowing to the dam. The weir diverts the first 10 cubic meters per second of water from the River Shannon along the old route of the river to maintain a flow for marine life. The next 400 cublic metres per second of flow are diverted along the head race (canal) to the Ardnacrusha dam. Any excess above 410 m3/ second (i.e. in floods) is again diverted along the old river route, through O’Briensbridge. See end of this post for a website link to photographs of serious flooding  in 2009 at Parteen Weir and elsewhere on the Shannon.

The Walk. O’briensbridge is on the West bank of the Shannon River. It is 16 km North of Limerick and 190km South West of Dublin. There is parking in two public car parks in the center of the Village along the riverfront. While there is a good surface for walking around the whole loop route, be warned there is a gate which needs to be climbed along the head race canal section. If you are pushing a buggy I would suggest just walking to the weir and back. Below is the route highlighted on Goggle Earth.

Walk along the River Shannon - O'Briensbridge to Parteen Weir
Walk along the River Shannon – O’Briensbridge to Parteen Weir (click to enlarge)

Below are some photographs I took along the route in early Spring this year:

Along the Shannon
Along the Shannon. The path between O’Briensbridge and the weir
Old cast iron bridge
Old cast iron bridge carries the path over a stream. The path was originally a tow path for horses dragging boats up the fast flowing river
Parteen Weir - Old Shannon side
Parteen Weir – Old Shannon river side
Another view of Parteen Weir
Another view of Parteen Weir, with lake water level visible behind
Parteen Weir - headrace side
Parteen Weir – headrace side. The raised gate on the left is to allow boats through
The headrace canal
Walking along the headrace canal towards Ardnacrusha Dam, 14km to the South and downstream
River level
The river level does vary below the weir, even in non-flood conditions. Above are two photos I took separated by 4 months at O’Briensbridge. Click to enlarge

During November 2009, the Shannon flooded severely. The water level rose around the Parteen weir area and elsewhere, there are some fascinating photographs on the Irish Country News Blog, click here.

There are lots of other walks you could try. For instance; The South Bull Wall, The Grand Canal, The Royal Canal, Bohernabreena reservoir, Dun Laoghaire Pier etc.

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