Iwi and environmental groups are challenging the council's claim a recent court ruling is irrelevant to the proposed Ruataniwha dam.
Iwi and environmental groups have challenged Hawke's Bay Regional Council's claim that a recent court ruling is "not relevant" to an ongoing legal argument over planning rules for the catchment where the Ruataniwha dam would be built.
An Environment Court decision last month upheld a challenge by Ngati Kahungunu Iwi Incorporated against a council attempt to drop a "no degradation" objective from its groundwater quality rules.
The council's bid to remove the objective was part of a long-running overhaul of land-use and freshwater management provisions within the regional resource management plan, known as Plan Change 5.
Now debate has shifted to the impact of the court's ruling on another update of the regional plan - Plan Change 6, which sets environmental rules for the Tukituki catchment where the Ruataniwha water storage scheme is proposed.
A board of inquiry is in the final stages of deliberating on Plan Change 6 and called for submissions after the council said the court ruling on Plan Change 5 was "not relevant" to the final decisions it has to make.
In its response, Ngati Kahungunu said the Environment Court decision on water quality and management was "highly relevant to the Tukituki and related groundwater resources".
Lawyers for three environmental groups which have challenged the Ruataniwha dam project - Fish & Game, Forest & Bird and the Environmental Defence Society - took a similar view.
In their joint submission to the board, the groups said the court ruling supported their argument that reduced in-stream nitrate limits for the catchment should also apply to the irrigation scheme.
Ngati Kahungunu said it had previously argued Plan Change 5 should have been settled before Plan Change 6 was considered.
Having the two plan change processes running at the same time had "created a considerable number of undesirable issues," the iwi group said.
That view was shared by another submitter, Napier Green Party spokesman Paul Bailey.
"The challenge that confronts us has been created by the applicant [the regional council] attempting to run numerous processes in parallel," Mr Bailey said.
"It is perhaps time to consider calling a halt to proceedings until the decisions that need to be finalised first are made first - in other words allow Plan Change 5 to be finalised before proceeding with Plan Change 6."
The board of inquiry has said it hopes to issue a draft decision on Plan Change 6 by the end of the month, which will then be open to comment from submitters.
Meanwhile the regional council has yet to decide if it will appeal the Environment Court decision related to Plan Change 5.
Regional Council Chairman Fenton Wilson said he had not been involved in any talks about a possible appeal.
"I wouldn't rule anything out or in at this stage," he said. We need to understand it a bit better and go from there."
Mr Wilson said he had discussed the court ruling with Hastings Mayor Lawrence Yule whose council had been involved in legal action over other parts of the plan change as an affected party.
He said the call to Mr Yule had been aimed at finding out how Hastings District Council's experts had interpreted the ruling, rather than to seek support for an appeal.
Mr Yule said his council was still studying the judgment.