Flooding in Ballyboy and Ballyglass

Ballyboy, Ballyglass is an area of South Galway close to Ardrahan and can be reached by taking a right turn at Ardrahan coming from Gort and continuing through the first crossroads. It is not part of the main water route from Slieve Aughty to the sea but there is some probable linkage to Slieve Aughty and because of poor drainage, it ends up flooding and causing crisis for many families in the area.



The Ballyboy drains from an area over 30m above sea level and for the most part the drainage consists of man-made drains that bring water from the Ballyboy, Ballyglass and Monksfield area into the Aggard which connects to the Dunkellin River and flows into Kilcolgan area to the sea.  These drains work their way across farmland and be seen on the map below.


These drains are not recent and if we go back to 1846 OS map we can see the drains and also the direction of the flow is marked as can be seen from the map below (Check out the OSI Map. )


There is one peculiar aspect of the drainage is that it flows in 2 directions.   The OS maps of 1846 show that the drains flow from the ruins of Cloghbroak Castle towards Ballyboy.   It also shows water flowing into Cloghbroak Castle from Monksfield but also water flowing in the opposite direction – so that water kind of appears out of nowhere.  Here is a summary of what this map tells us.


In general, the land is very flat the flows we are talking about are not substantial. These are not rivers but drains and some of the culverts are only 12-inch pipes. There is a very small flow that sinks in a swallow hole close to Ballyboy that can be seen on the diagram below.


The other drainage aspect is that there are flows beyond the castle that join with the  Monksfield river flow and flow into the Aggard stream.

Severe Winter Flooding

It’s hard to really understand exactly what happens in when we get rainfall like we did in 2009 and 2015 but it has a big impact on Ballyboy and Ballyglass.  The area around Ballyboy becomes badly flooded as can be shown in the photograph below.

Ballyboy area flooding, showing Forde’s house and the Ballyglass road is under water (Courtesy of Sean Brady Aerial Photography)
The Ardrahan-Ballyboy road has been raised several times to help keep access for houses, farms and farm buildings. (Courtesy of Sean Brady Aerial Photography)
The extent of the flood is captured looking westward . (Courtesy of Sean Brady Aerial Photography)

The following diagram shows the flooding on a map. (Compiled from Sean Brady’s photos and flood maps – Copernicus project)


Cause of the flooding

It’s hard to pinpoint the source of the flooding but the Ballyboy area has many wells and springs.  It may have a similar dynamic to Cockstown where a spring starts to overflow  (from pressure in Grannagh)  and flow into Tulira.   It may be that when Blackrock Turlough rises to 30m above sea level, this starts to put pressure on underground channels from Grannagh and Blackrock towards springs  in Ballyboy. In fact, it wouldn’t surprise me if the small swallow hole in Ballyboy changed direction and became a source and started outputting water into Ballyboy. (This is called an ‘estavelle‘ and also happens in Ballylee, and other places) .   The levels seem to build until it reaches Cloghroak Castle which then flows (Slowly) towards the Aggard.

Flooding impacts

The main impacts of the flooding are

  • Flooding of homes
  • Access
  • Farming

As the levels in Ballyboy rise they start impinging on several houses in Lackan and they needed protection.  A bund (dam) was built in the past to protect these houses but in winter 2016 sandbags had to be added to the top of this bund to keep the water away from these houses.  Also in Ballyglass, close to Cloghroak castle a house was threatened and required protection (Sandbags etc.)

A major impact for the area was access.  The road from Ballyboy to Ballyglass was under water and impassable from 11th of December to the 25 of Feb (76 days).  This meant that access to the school of Ballyglass was severely restricted during this time for pupils form the Ardrahan/Labane side (made worse by flooding of the Cockstown road. The impact of school access cannot be underestimated and could up to several 100s of km a week extra, doing runs and drop-offs.  A repeated occurrence of this type of flooding and horrendous access impacts would have dramatic impacts for the future of Ballyglass school.  No parent wants to add an additional 500km to their school run every week for 7-8 weeks.

This also had a big impact for farms both in terms of restricted access to farms due to roads flooding or the land being flooded.  A major impact is that the flood water stayed on the land up until May 2016 almost 5 months after the floods came.


The flows don’t look substantial and the flood levels are not very deep e.g. an average 2ft-3ft deep compared to 25ft-30ft in a Blackrock/Caherglassaun flood. It wouldn’t take much to flood the area.  A flow of about 1m3/sec would flood this type of area to a 1m level in 5 days.

From an initial look at this the solution to flooding in this area should not be complex.  These are not big flows but they are allowed to rise and stagnate – blocking roads and access and threatening houses.  While the water still sits in Ballyboy in April, the Aggard River is very low and due to poor drainage.

There seems to be several local concerns about the impact of rising of the Ballyboy roads (from Labane to Forde’s house) but this  would appear to have very little impact on the overall flooding. The foundation is essentially porous (made from small rock)  and will not hold water back. As the Ballyboy levels rise and expand, the water simply seeps under the road into the fields on Forde’s /Fahy’s side. The levels will be the same both sides of road. It’s when a road threatens to  block a flow that is usually the cause of main concern.

The bund close to Harris’s house will not have a major impact on flooding by holding water back. The bund probably protects less than an acre of ground (with 2 houses and road access) and there is probably over 140 acres flooded in Ballyboy so even if the bund held back an an average of 3ft deep of water displaced by the bund, this would amount to a rise of 6.5mm across the 140 acres.


It’s all about the levels and having a good look at these should help shed some light on the flooding dynamics.  However, there are some things to consider.

The  man obvious solution is to improve the drainage to the Aggard River.    These drains have been there for 100s of years but need proper maintenance.  Remember we are probably not talking about a major flow here. When the Dunkellin scheme finishes there should be additional capacity in the Aggard, and a reasonable solution would seem to be to profile the Ballyboy and Monksfield drainage.

A conservative solution could be to improve the drainage but put a sluice gate in to control the levels.  Local farmers have indicated that in March the Aggard stream was very low but there was still a large body of water in Ballyboy – imagine if you could use that spare capacity over a few days with a result of ensure a fully accessible school.

Without having any detailed data but speculating from the 1846 maps, the area around Cloghroak castle seems to be the critical point.  The maps show water flowing downhill into Ballyboy so this indicates that Ballyboy is in a basin (with it’s own swallow hole) but if that swallow-hole stops working (or, even worse reverses)  then Ballyboy will have to rise  until it finds the outlet on the Monksfield side of Castle.

On the positive front, the Dunkellin Scheme is progressing, the engineers involved will know what type of additional capacity the Aggard can take.  This area has man-made drainage for 100s of years and this drainage needs to be improved to help eliminate the threat of flooding to peoples homes, keep Ballyglass school accessible and reduce the time that land is flooded for. This should be possible without threatening neighbouring communities.

At several of our public meetings our local representatives have stated that once Dunkellin scheme is complete -Ballyboy improvements should be considered in a supplementary works.

David Murray

(If you have any additional information then please let me know)



Author: David Murray

Dave is a 'Solution Architect' with a hi-tech company called Arm. He is deeply involved in his community and his two key focuses are based around the rivers of South Galway. He is an activist in getting flood relief solutions in place for South Galway after decades of empty promises and also is also helping to progress a beautiful Gort River Walk for the South Galway/North Clare communities.

One thought on “Flooding in Ballyboy and Ballyglass”

  1. Hi David, my name is Kevin Kyne I live a mile or so from Monksfield and had my own “issues ” with flooding.
    If you have a minute Id like to chat to you at some stage as I have no joy with Galway Co Co.
    Kevin 0879598571

    Liked by 1 person

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