The Minister for Foreign Affairs has been asked to help in the effort to obtain permission to build a new water treatment plant at Lough Talt in south County Sligo.
The application is being made under European legislation that allows a special case to be made when a project is needed in circumstances of Overriding Public Interest, despite it being in an area of special conservation.
The Minister with responsibility for heritage, Josepha Madigan, must sign off on the application as a previous planning application was unsuccessful because of sensitive species on the lake foreshore, including the Arctic Charr fish, a rare snail and the Oak Fern plant.
A Boil Water Notice was reissued for the supply last January, after having been lifted only in October 2018, affecting more than 13,000 customers.
That notice followed the discovery of cryptosporodium in the water.
Yesterday in the Dail, Sligo/Leitrim Deputy Eamon Scanlon asked Simon Coveney to speak to Minister Madigan.
Simon Coveney said Irish Water was improving the system, adding that planning delays was frustrating for it too.