The Supreme Court hearing about land needed for the Ruataniwha Water Storage Scheme has wound down.
The hearing at New Zealand's highest court ended on Tuesday - where the Minister for Conservation and Hawke's Bay Regional Investment Company appealed a 2016 Court of Appeal decision.
In September the court had upheld a Forest & Bird appeal that the proposal to exchange 22ha of the land for 170ha of land the Hawke's Bay Regional Investment Company LTD (HBRIC) would potentially buy from Smedley Station, was unlawful.
This would have downgraded the protected conservation status of the Ruahine Forest land to allow it to be flooded as part of the water storage scheme.
Lawyers on behalf of DoC spoke on Monday, followed by Forest & Bird lawyers on Tuesday.
Forest & Bird's lawyers focused on what level of protection forest parks have in law, and whether it is permitted to downgrade forest park land in order to exchange it.
Forest & Bird chief executive Kevin Hague said the country's conservation law only allowed the stewardship category of conservation land to be exchanged or sold.
"Our legal team argued that the Minister of Conservation's decision to downgrade Forest Park land in order to swap it eroded a key distinction between the two categories of land," he said.
Their counsel - Davey Salmon and Sally Gepp - asked the judges to consider the effects of allowing forest parks to be treated as if they were stewardship land.
Mr Hague said this suggested this would make all Forest Park land vulnerable to commercial exchange or sale.
Ms Gepp said the environmental agency's concern was the Minister's decision to downgrade the land in order to swap it was not parliament's intention of parliament when they passed the Conservation Act in 1986.
"The case we presented to the Supreme Court justices is that the decisions to downgrade and to swap must be made independently of each other, and that did not happen in this case," she said.
Currently, activities relating to the Ruataniwha scheme are on hold as the Hawke's Bay Regional Council conducts a review on it - this does not extend to the Supreme Court case, but does prevent HBRIC acquiring the land through other means.
It was not known when the hearing judgement would be released.