Taking Lough Neagh into public ownership would be inadvisable and would come with a price-tag of at least £6m, it has been revealed.
A long-delayed Stormont report warned taxpayers would also have to meet the on-going costs of management and administration – along with the potential cost of third party liability claims.
The report by an expert panel advised the Assembly against moving towards nationalisation of the lough, owned by the estate of Lord Shaftesbury, which supplies Northern Ireland with 45% of its water.
It said it had been "unable to identify any tangible benefits" to the management of the waterway should it be taken into public ownership.
It said key interest groups were divided on the issue – almost half were totally opposed but some of those in favour had significant reservations – and instead recommended a new "over-arching" management structure for the future.
The report also revealed that while owners of the Shaftesbury Estate had no plans to sell the lough, "that does not mean if the Assembly asked to buy it the answer would be no".
The experts warned that purchasing the entire area would involve negotiatons with around 60 separate owners of small parts of the area, the biggest freshwater lough in Western Europe at 150 square miles.
Now Agriculture Minister Michelle O'Neill, who had said the nationalisation could be achieved by either compulsory purchase or an agreed sale, revealed she was to move forward with a more "representative public management structure".
Sinn Fein Mid Ulster MP Francie Molloy argued that the lack of overall responsibility for the lough prevented a strategic approach for its future development.
MLAs united to ask Ms O'Neill to convene a working group to explore the potential for a cross-departmental approach to bring Lough Neagh back into public ownership, but its report had sat on the shelf in Stormont for more than 18 months.
Ms O'Neill came under fire in the Assembly when the DUP's Paul Frew, chair of the committee that monitors her department, argued: "It was very clear that Sinn Fein wanted to take the lough back into public ownership.
"We do not need to do that, we just need to manage it better, and that does not require taking ownership of it."
His DUP colleague Jim Wells, the only MLA who has worked on the lough, said his personal view was that the Assembly should move to "voluntarily purchase" rather than vest it, and said he believed the Earl of Shaftesbury could prove amenable to such an approach.
SDLP deputy leader Dolores Kelly also spoke in favour of nationalisation.
"The ecological environment around the lough has deteriorated in the past couple of decades.
"For that reason alone, one could argue that the lough should come back into public ownership," she said.
The report said the Earl believed the £6m figure arrived at during his father's tenure was "fair and not exorbitant", but there would also have to be a formal valuation, which would include mineral rights.
It said there was no risk to water supplies.
Land-locked Lough Neagh has had mounting problems in recent years, among them:
- Bacteria that led some councils to ban watersports.
- Eels once sold at top prices because they lasted two months now last only 10 days.
- Plummeting migratory bird populations.
- The theft of fish stocks.
- Yet, the water quality is said to have slightly improved.