Michelle O'Neill has faced criticism over her response to the Lough Neagh crisis with opponents claiming the Sinn Féin deputy leader failed to put an effective management plan in place while she was Stormont agriculture minister.
The first minister designate tweeted on Thursday that Sinn Féin supported taking the lough into public ownership, however, a civil servants' report she commissioned while agriculture minister in 2012 found there were no "tangible benefits" to nationalisation.
The report instead advocated an "overarching management structure" which was never implemented.
The bed of the lough and its banks belong to the Earl of Shaftesbury, while a variety of Stormont departments and arm's length bodies are responsible for its governance.
Ms O'Neill said an "urgent action plan" needed to be developed to tackle the toxic algae that covers swathes of Lough Neagh.
"As the largest lake on the island and an area of astonishing natural beauty, it’s a huge asset for the local community who live on its shores and has so much untapped potential," she said.
"Sinn Féin has long advocated that Lough Neagh should be brought under public ownership so that a clear management structure and long-term plan can be developed to ensure the lough is safe, sustainable, and flourishes for future generations."
But Ulster Unionist environment spokesperson Tom Elliott, who is opposed to taking the lough into public ownership, said the former agriculture minister's remarks were "incredulous".
"Instead of producing direction that could have prevented much of what we face today, she, along with party colleagues, pushed for public ownership of Lough Neagh, something I see her calling for again, 11 years on," he said.
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"As my party highlighted at that time, public ownership was not, and still is not, the answer – I use Lough Erne as a key example of a lough in public ownership that cannot bring stakeholders together effectively to address issues."
The SDLP said it was "disappointing" that the opportunity to take Lough Negah into public ownership was never realised and that "momentum around the issue was lost".
"The failure to implement a proper management structure for the lough has directly contributed to many of the issues we are now dealing with and the lack of accountability that has added to the difficulty in addressing the problems," a party spokesperson said.
A Sinn Féin spokesperson responded to the criticism by saying public representatives and political leaders "need to focus on finding resolutions to the serious issues at Lough Neagh".
Meanwhile, it has emerged that plans to relax restrictions on sand dredging from the bed of the lough would have been approved if Mid-Ulster District Council had not raised concerns.
Lough Neagh Sand Traders Ltd, a body representing all five firms involved in sand extraction, had asked the Department for Infrastructure (DfI) to allow them to use larger dredging barges and extend the hours they could operate.
According to The Detail news website, DfI was "minded" to grant planning permission to relax restrictions before the council intervened. The department said it plans to write to the Planning Appeals Commission to arrange a hearing on the application.
