The long-running Ruataniwha irrigation scheme saga will now head to the High Court as several environmental groups challenge the Board of Inquiry's final report.
The proposed $600 million scheme could irrigate 25,000 hectares of Hawke's Bay farmland.
Last month the board confirmed it would grant 17 resource consents to build the water storage scheme and associated irrigation works, and Plan Change Six, which sets minimum flows and water quality measures for the Tukituki catchment.
Two enviornmental lobbied, Fish and Game and Forest and Bird have confirmed that they will challenge the report in the courts on points of law.
Fish and Game chief executive Bryce Johnson said his members have a problem with the changes made by the Board of Inquiry between its draft and final reports.
"Our simple concern was that the way in which the judgement has been changed from the draft to the final version will probably render the decision - I don't say in-operative - but not that effective in achieving the outcomes of water quality protection in the Tukituki River."
And Forest and Bird's advocacy manager Kevin Hackwell said it believed the Board of Inquiry had made a mistake in law by not including any methods on how its water quality pollution limits could be met.
"We think the Board of Inquiry has failed in a couple of important points of law," he said.
It set good limits on the nutrients that could go into the river, particularly issues around nitrate nitrogen and dissolved inorganic nitrogen.
But having set those it didn't actually as is required by the National Policy Statement on Freshwater Management it didn't provide methods for achieving those limits.
And that's the key thing we're going to them on."
The Hawke's Bay Regional Council and its investment arm have said they will not appeal the Board of Inquiry decision.
The irrigation industry body recently said it was pleased with the board's final decision which it said had decoupled nitrogen limits from individual farms.
The Ruataniwha scheme has had repeated set-backs recently with proposed cornerstone investors Trustpower and Ngai Tahu walking away saying it wasn't worth the risk, and the Central Hawke's Bay District Council also recently deciding not to invest.