HBRIC's chief executive Andrew Newman said this latest appeal against the department's decision was another attempt to delay the progress of the Ruataniwha Scheme, despite Forest & Bird previously publicly stating that was not its objective.
He said the department undertook an extremely robust process in deciding the land exchange.
"I would have thought Forest & Bird had achieved any legitimate goal of clarifying the law around land exchanges of this kind for the future, and to launch another appeal against another aspect of the scheme is simply trying to block progress," Mr Newman said.
These comments angered regional councillor Rex Graham who said he was "horrified and embarrassed" at the suggestion that Forest & Bird was trying to delay the scheme.
"Claiming that Forest & Bird's motivation is to delay the scheme is insulting and a blatant attempt to demean a legitimate group of our citizens who are exercising their legal rights," he said.
Forest & Bird's Hawke's Bay conservation and volunteer manager, Amelia Geary, said this matter goes far beyond Hawke's Bay and the Ruataniwha dam.
"Even though the Ruataniwha dam project is looking unlikely to proceed given the recent drastic slump in dairy prices and farmers' reluctance to sign up to buy water from the scheme, it is still important to challenge this precedent-setting decision," she said.
Forest & Bird solicitor Sally Gepp said the main reason for the group's appeal is that it believes that the High Court was wrong to find that a decision to revoke the status of specially protected land in order to enable it to be given away in a land swap deal.
"Allowing this decision to stand could mean that any part of New Zealand's specially protected conservation land can be traded away and the special values of the land removed to advance commercial interests," Ms Gepp said.
"It sets a precedent for up to one million hectares of specially protected conservation land throughout New Zealand, which includes forest parks, conservation parks, and ecological and wilderness areas."
She said the judge made the point that this case goes to the heart of the purpose of the Conservation Act, which is why it is such a significant case for Forest & Bird, and for New Zealand.
"We believe the High Court was wrong to hold that the decision was consistent with the act's purpose."
Mr Newman said the most likely outcome, even if the appeal succeeds, is for the land exchange decision to be handed back to DOC to require them to undertake the process again in a more precise sequence.
"This scheme has the potential to create jobs and inject new life into Hawke's Bay at the same time as improving the Tukituki River," he said.
"Forest & Bird refuse to see that and are determined to stall the progress every step of the way."
Mr Newman said the focus remains on confirming all elements of the scheme with many tasks completed or approaching completion.