Uisce Éireann has halted work on a wastewater connection at a new Supermac's motorway service station in Co Clare, pending the outcome of a legal challenge taken by an environmental group.
The Banner Plaza, located outside Ennis on the M18 motorway linking Galway to Limerick, had been due to open later this month.
The company said the new development, which has so far cost around €18 million, will create 120 jobs when operational.
In August, Friends of the Irish Environment (FIE) launched a High Court legal action against Uisce Éireann over its connection agreement for the plaza.
The environmental group said it was pursuing a judicial review because the connection being made to the Clareabbey Wastewater Treatment Plant was "already overloaded".
Today, the High Court was told that Uisce Éireann had suspended its work on completing the connection and that 14 days' notice would be given before any work resumed.
Counsel for Supermac's, Alan Keating SC, told the court that the company would be seeking leave to challenge any application from the applicants for cost protection.
Mr Justice Richard Humphreys put the case back for mention on 3 November.
Friends of the Irish Environment previously claimed that the Clareabbey WWTP was "operating above its licensed capacity since 2008" and adding the new development would "push this even higher".
"In late 2024, the Environmental Protection Agency (EPA) confirmed the plant was serving 6,150 'population equivalent' (PE) despite a maximum capacity of 6,000 PE."
FIE also said data provided by Uisce Éireann to the EPA showed that between March 2023 and October 2024, the plant's "limited treatment capacity" had already led to "raw or partially treated wastewater" being discharged into the Fergus River and its estuary.
In response to the move in August, Supermac's said the Banner Plaza project had already been the subject of "detailed consideration and a full judicial review".
The fast food restaurant chain said the High Court "rejected similar arguments and confirmed the decisions of Clare County Council and An Bord Pleanála" in September of last year.
In a statement, the company said: "The judgment noted that there was no evidence to support the suggestion that the treated water from the plaza would adversely affect the output from the Clareabbey treatment plant."
And Supermac's said legal challenges against post-planning connection agreements "undermine the integrity of the planning system, which is designed to provide certainty once decisions have been made and upheld at the highest levels".
The company first applied for planning permission for the development in 2014, which it eventually secured in October 2022.
The construction work began earlier this year after a judicial review against An Bord Pleanála, now An Coimisiún Pleanála, taken by a local environmentalist was dismissed by the High Court.
That case, taken by Michael Duffy, also related to capacity concerns at the Clareabbey Wastewater Treatment Plant.
