The Department of the Environment has come under fire after it emerged that signs of pollution have been found in a tributary of the River Faughan, next to the huge illegal waste dump at Mobuoy.
Environment Minister Mark H Durkan said pollution has been found in the stream next to the site, which was Europe's largest illegal dump.
The minister said 1,426,435 litres of contaminated surface water have now been tankered off the City Waste site in Co Londonderry and treated at a local wastewater treatment works.
"No significant pollution has been identified in the River Faughan. There has been some pollution in the local stream adjacent to the site – however a visual inspection by NIEA staff in April noted that this has receded," Mr Durkan said in response to an Assembly question from the Green Party's Steven Agnew.
Last night Friends of the Earth said it was "beyond imagination" that pollution was still happening at the site.
"This illegal dump was one of the biggest in Europe and the DoE did not respond for years. It appears they are still not responding to stop pollution in a river from which most of Derry gets its drinking water," NI director Dr James Orr said.
"After the Mills Report and after the expose on BBC Spotlight we need to find out why this river is still being polluted. Who will regulate the regulator?"
Meanwhile, a spokesman for the River Faughan Anglers said he had walked the stream two weeks ago and noticed sewage fungus.
"I also noted signs where leachate had seeped from the illegal landfill directly into the stream, staining the ground at five separate points," he said.
The spokesman said the anglers had taken photos in April 2013 showing that the illegal landfill had increased and encroached further on to the stream since a year previously.
"Only one week before we photographed this significant encroachment on to the stream in April 2013, DoE planning wrote claiming 'no significant works were being undertaken within 10m of the stream.' This was simply not true," he said.
The Department of the Environment warned of scaremongering, saying no significant pollution has been identified in the River Faughan.
"There has been a significant improvement in the condition of the stream over the past six weeks. While there is no obvious pollution, the amount of fungus in the watercourse, indicating pollution, has substantially disappeared," a spokesman said.
"Far from NIEA not responding, the opposite is the case. We are aware of the need to deal with the short-term and longer term potential environmental impacts of the illegally dumped waste on the Campsie Sand and Gravel and City Waste sites, given that they are close to the River Faughan.
"Immediately following the closure of the sites, NIEA implemented an emergency leachate management programme to try and afford immediate protection of surrounding streams.
"NIEA have also implemented a detailed water quality monitoring programme, with the aim of determining if there was any immediate, longer-term or large-scale polluting impact on the river from the waste sites. This will continue until a project has been completed to consider the longer-term future of the sites."
Story so far
In 2011 the DoE found that more than half a million tonnes of illegal waste had been buried without permission around a licensed recycling site at Campsie near Derry. Independent expert Chris Mills noted a history of non-compliance with regulations at the licensed site, but said it was still not known who had deposited the illegal waste. To date 4,786 tonnes of waste, 2,458 tyres and 1,426,435 litres of leachate have been removed from the site at a cost of around £800k.