Wicklow County Council approved building developments within a safety area surrounding sensitive regional reservoirs and streams, it has emerged.
The developments of holiday accommodation, housing, landfilling and quarrying were approved within the last four years, contrary to the water quality management plan for the Liffey catchment drawn up to protect drinking water supplies to Wicklow, Kildare and Dublin.
According to papers released by Dublin City Council under EU access to information legislation, the city made more than 20 objections to the Wicklow council, including a submission to the draft county development plan, and appealed individual planning applications to Bord Pleanála, during the last four years.
The city council said the developments "seriously" threatened 340 million litres of drinking water that are supplied daily from the city's reservoirs at Poulaphouca and Roundwood.
Surveys by consulting engineers Binnie and Partners have also indicated the Poulaphouca reservoir is tending to become eutrophic (deficient in oxygen) due to a rise in nutrient levels, part of which is attributable to septic tanks.
The finding was confirmed by An Foras Forbartha and the city council's own water-quality analysis over a number of years.
The city also reminded Wicklow County Council on a number of occasions that the aim was to protect Poulaphouca reservoirs, streams and tributaries, which provide 50 per cent of the drinking water in the greater Dublin region.
The Foras Forbartha water-quality management plan recommended control of development around the perimeter of the reservoir and a ban on septic tanks or percolation areas within 200 metres of the shoreline or within 100 metres of any drain or stream leading to the reservoir.
Dublin City Council also told Wicklow County Council that the standard should be applied to the Vartry reservoir in Roundwood and that there was a serious danger of pollution to water supplies there, due to inappropriate development in Roundwood.
The correspondence shows that, despite the warnings, Dublin City Council decided it had to follow through with individual objections to and appeals against an apartment-hotel, a golf clubhouse and effluent treatment system at Tulfarris House on the Blessington lakes; an extension to the Roadstone quarry at Blessington; three separate landfills at Blessington; a waste processing station and landfill at Crosscool Harbour; a waste permit at Monaspic, Blessington; a housing and apartment development at Roundwood, and a number of applications for single houses.
