Geologists who have discovered freshwater aquifers running between the Burren and the Aran Islands believe further research would establish the full extent of the sub-sea link.
Natural conduits running under Galway Bay have already been identified as the source of freshwater on Inis Meáin.
However, they could be a fraction of a far more extensive network of caverns, according to Dr Tiernan Henry of NUI Galway’s (NUIG) school of natural sciences.
The significant discovery on Inis Meáín was made by NUIG researchers following conversations with residents who said their well of fresh water never ran out, in spite of the summer water shortages experienced by neighbouring islands.
One well on Inis Meáín ran deep into the rock and was getting more water than that which fell as rain on the whole island, Dr Henry noted.
Mayo-based water diviner Paddy Murphy says he is not surprised at the discovery, as he believes there are extensive freshwater caverns on the southernmost Aran Island of Inis Oírr, if they can be tapped.
Inis Oírr has suffered chronic water shortages, posing challenges for Galway County Council.
Prof Colin Brown, director of NUIG's Ryan Institute, says he recalls how Galway County Council officials and locals knew 30 years back about brackish water in deep wells in the south of the county near the coast, without necessarily knowing why.
“There were lots of anecdotes from fishermen about certain spots in Galway Bay where one could drop a kettle and fill it with freshwater for tea,” Prof Brown says.
Galway Bay oyster farmers and anglers had also referred to freshwater “risings” along the south rim of the bay as far west as north Clare’s Black Head.
The researchers believe that the conduits, which could be up to 30 miles long, are caused by water falling on land and dissolving the limestone that underlies southern Galway and north Clare.
This is the same karstification process that slowly created the distinctive topography of the Burren, Dr Henry explains.
The same pure bedded limestones that form the islands are found throughout north Clare and south and east Galway.
The deepest part of Galway Bay is about 50 metres, with an average depth of between 25 and 30 metres.
