A "David and Goliath" story is unfolding as an environment group prepares to challenge the science behind changes to the way the Tukituki catchment will be managed.
The Hawke's Bay Regional Council rubber-stamped its Tukituki plan-change document at its meeting yesterday, and chairman Fenton Wilson labelled it a "major milestone".
A major section revolved around setting nitrate and phosphorus limits for land users, to control nutrients leaching into the catchment.
Mr Wilson said it was an area which had inspired opposition from some parts of the community.
"But those groups feeling disaffected will have ample opportunity to support the claims they have around nitrate," he said.
"There are no secrets here, it's all in front of us. People will have a chance to present credible scientific evidence to counter aspects of the plan as they see fit."
The council was told the catchment was "over-allocated" or had higher than desirable levels of phosphorus, which must be reduced, but nitrate levels were "within the limits".
The plan will go out to the public for comment on May 4. It will then be handed over to the Environment Protection Authority to review in June and people will have a second chance to comment.
One group likely to submit is the Te Taio Environment Hawke's Bay Forum.
Its spokesman, John Cheyne, confirmed it was the level of nitrate the plan allowed for in the Tukituki catchment that was the point of contention.
"What I understand is that the level of nitrate will go up by as much as 560 per cent and we are keen to see the scientific report that supports this information," Mr Cheyne said.
The group would submit to the plan and "get involved again" when it went to the authority.
"But this is very much a David and Goliath situation. We don't have the resources that the regional council has in terms of staff, expertise and dollars," he said.
"Environment groups don't get funding from the council. But we are looking at some assistance to get advice from a solicitor who has RMA (Resource Management Act) experience to help us present our submission."
The Tukituki plan change is connected to the regional council's plan to build the Ruataniwha water storage dam in Central Hawke's Bay.
Mr Cheyne, who is also a biodiversity officer with Fish and Game, said the group had not declared itself opposed to the dam but had some "environmental bottom lines" it was not prepared to move on.
"I think you will find that most of the people in our group would support the dam if those bottom lines were met."
Councillors were told that the rules and regulations of the plan change would go ahead even if the dam wasn't built.