An independent watchdog has launched an investigation into the unauthorised extraction of sand from Lough Neagh.
The Northern Ireland Audit Office probe is understood to be at an early stage and is expected to be completed later in the year.
Environmental groups have voiced concern after it emerged that a number of sand extraction firms have ignored a request from environment minister Mark H Durkan to halt their activity because they have no planning permission.
A spokeswoman for the DoE last night said the audit office "has initiated a review of environmental protection of Lough Neagh."
In a letter to five companies last year Mr Durkan said that dredging sand from the lough "is unauthorised and the activity should cease until this situation has been addressed".
To date the DoE has also failed to carry out any enforcement action and has claimed the issue "is the subject of an ongoing investigation."
Large sand barges involved in sand extraction can be seen travelling on Lough Neagh on an almost daily basis
It is estimated that up to 1.2 million tonnes of sand are taken form Lough Neagh each year.
A fee is paid for every tonne of sand taken from the lough to the Shaftesbury Estate, which owns the lake bed.
The sand extracted from the lough is favoured by the building trade.
As Ireland's largest freshwater lake, Lough Neagh is designated as a Special Protection Area. A Ramsar site and is also an Area of Special Scientific Interest
James Orr from Friends of the Earth welcomed the development.
"We are very pleased that someone independent is looking at this," he said.
"The problem is there has been no independent assessment of the management of the lough.
"I should be one of our most special places but there is no management it seems to us.”
"The minister asked last year for sand dredging to stop but they are out every day, it seems their activity has increased instead of decreasing."
Mr Orr said that there are concerns over bird numbers and fish stocks in the lough.
He said that after years of neglecting environmental issues it is now "impossible to access what these environmental impacts are."
Green Party assembly member Stephen Agnew said the DoE could be leaving itself open to fines from Europe.
"I hope that the investigation is thorough and looks comprehensively at our shambolic planning enforcement system," he said.
A spokeswoman for the department said it will continue to "engage with the NIAO through the course of this review."
"Given that there is an on-going enforcement investigation and follow up action by the department the permanent secretary felt it would be inappropriate to meet with the Friends of the Earth to discuss the case."
