1,600 tonnes of waste are dumped near water supply
The cost to clean up 1,600 tonnes of waste illegally dumped near the Border could stretch to €2m.
It is understood that the waste was being ground down using machinery and was then mixed with organic material such as chicken manure before being buried or spread on the land in Co Louth.
The land the waste was dumped on, and possibly buried in, at times runs close to the River Fane, which supplies the Cavanhill water treatment plant for Dundalk and environs.
There were concerns raised last year about possible contamination of the river from diesel laundering.
Yesterday, Fianna Fáil deputy Declan Breathnach said: "I have had many concerns in the past about fuel-laundering plants causing contamination to our water supply.
"On foot of complaints, the county council decided to carry out investigations and they have unearthed approximately 600 tonnes of material in close proximity to the River Fane.
"Louth County Council then carried out further searches and has discovered a further approximately 1,000 tonnes of municipal-type waste and organic material upstream, which probably accounts for the pungent odours complained of by local residents."
Louth County Council said: "Enforcement action under the Waste Management Acts has been initiated by the council in respect of a premises located in the River Fane catchment.
"Investigations carried out do not indicate any immediate risk to water quality in the river."
Irish Water said it had "all the necessary protection and water treatment barriers in place at the Cavanhill water treatment plant to ensure there is no risk to the public water supply. Daily water sampling and monitoring are undertaken."