Hawke's Bay Regional Investment Company says it is confident a proposed swap to free up Department of Conservation land required for the Ruataniwha dam will be approved in time to keep the project on its current schedule.
But the company - Hawke's Bay Regional Council's investment arm and the promoter of the Ruataniwha scheme - says it can not rule out the possibility of a subsequent legal challenge having an impact on the project.
Environmental group Forest & Bird is among those who have challenged plans to swap 22ha of Ruahine Forest Conservation Park land for 146ha of property owned by Smedley Station so the current park land can be flooded to create a reservoir as part of the Ruataniwha irrigation scheme.
DoC has run a public consultation process but is yet to make a final decision on the proposed land swap although it indicated late last year it believed there would be "an enhancement of conservation values if the exchange were to be effected".
Forest & Bird has challenged the department's assessment, saying there were "shortcomings" in its analysis.
HBRIC chairman Andy Pearce said the company expected a decision from DoC ahead of the November deadline HBRIC was working towards for finalising funding, farmer sign-up and construction contracting details for the $275 million Ruataniwha project.
At that point it plans to go back to the regional council for final approval to go ahead with a planned $80 million ratepayer investment in the project.
Dr Pearce said HBRIC was "reasonably sure" the end result of DoC's decision-making process would be "a positive outcome" for the project. But he said there was no certainty if the issue became the subject of a subsequent legal challenge, such as a judicial review of DoC's decision.
"We've got no reason to think there's any basis for a judicial review but that is not to say that parties might not attempt to have one just to throw another delay into the process. That would be an interesting test of people's morals and ethics," he said.
Chris Perley, a spokesman for lobby group Transparent Hawke's Bay, which has opposed the dam, said from a project management perspective, HBRIC should have sorted the land-swap issue out "way back".
"Suddenly it's become an 'oh, no' thing. It's not exactly a sign of confidence," Mr Perley said.
Dr Pearce said the possibility of seeking a judicial review over the land-swap was the only option left to opponents of the project who had fought it unsuccessfully through a board of inquiry process.
"They are left with frustration, delay and scaremongering as their only tactics and we're seeing those tactics being played out."