Forestry agency Coillte has had to spend more than €950,000 over the past two and a half years cleaning up after illegal dumping on its lands.
The semi-State company said there had been nearly 250 dumping incidents in its forests since the beginning of 2022.
Illegal waste was especially problematic in Co Cork with 52 cases of dumping reported in west Cork and a further 18 in east Cork.
Coillte said altogether over the past five years, its clean-up and disposal bill had come to around €2m.
Figures released following an environmental information request show that the bill to rectify illegal dumping in 2022 was just over €331,000.
A further €350,000 was spent in 2023 and in the first six months of the year, Coillte's clean-up costs had already reached €270,000.
The agency said it took illegal dumping extremely seriously and it worked closely with gardaí and local authorities to combat it.
It said signs, barriers and CCTV were all used to deter the ditching of waste, particularly at "hotspots across [its] forest estate".
A log of incidents showed that there were 245 reports of illegal dumping since the beginning of 2022 with 50 in the first half of this year alone.
Aside from Co Cork, other areas with a high number of cases were Clare with 19, Laois with 18, Tipperary with 17, and Galway with 15.
In some counties, there were few reports, but figures can depend as well on how much land Coillte manages in each area.
A litter policy for staff from the forestry agency said incidents needed to be dealt with quickly to avoid locations becoming "blackspots" for dumping.
It said each forest needed to have a security and fire plan and that CCTV should be considered for areas deemed of "high risk".
Asked about illegal dumping, Coillte said it caused serious problems for habitats, species, waters, soils and human health.
"It can pollute rivers and drinking water sources, damage biodiversity, and is a threat to both the people who live in an area and recreational users. It also poses risks to Coillte staff who have to remove this illegally dumped material," a spokeswoman said.
Reporting by Ken Foxe
