A document which suggests how the Tukituki River catchment could be managed has been criticised as "fatally flawed" and a biased piece of work written by the Hawke's Bay Regional Council.
The council is about to officially release its Tukituki Choices document which outlines four options for land and water management of the catchment. There are two options which involve water storage projects, one includes the initiative on the Ruataniwha Plains in Central Hawke's Bay.
Five members of the Ruataniwha Water Storage Group, headed by Tom Belford, wrote to the council to tell of its "extreme disappointment" with Tukituki Choices.
The group said the council agreed to its request for a draft of the document, prior to its public release.
"That advance circulation unfortunately did not occur. We consider that a serious breach of trust, which accounts in part for shortcomings in the document that render it deceptive as a public consultation tool."
The group also believed the council used its own view on the science involved in the project, especially when it came to the environmental protection for the catchment, the measures to deal with ecological problems and the cost of those measures.
It also wanted Tukituki Choices to reflect that some environmental specialists challenged several science aspects of the work the council had undertaken "so the public would clearly be informed - that request was ignored".
The group's independent chairwoman, Debbie Hewitt, said the letter did not represent the views of everyone on the group.
"We've been working together for the past 2 years without any problems but part of the journey is that there will be some concerns along the way."
The council's chief executive Andrew Newman said the group's opinions were not "necessarily the facts".
He said there was no record of an agreement to share the document before its release "but certainly it was thought the stakeholder group would have a role in the consultation phase".
He said Tukituki Choices was based on wider public comment, to find out what people wanted for the river's catchment and it would be ongoing, not finalised in a single document.
Mr Newman acknowledged the group disputed some of the science in the document, particularly around the nitrate toxicity report. But his project team had no doubt over the validity of the science used to carry out assessments.
"As you can see from what has been outlined there is a difference in expectations around the role of the stakeholder group in the Tukituki Choices document.
"The stakeholder group has been involved in the setting of the overall direction of the document but it is ultimately a HBRC document."
Mr Newman said the document was not a tool for scientific presentation but brought together options for people to consider.
People can have their say on Tukituki Choices by writing to the council by October 5.
Tukituki choices Options to manage the Tukituki River catchment:
Option A: Caps water allocation limits at current consented volumes and sets a high level of protection for long-fin eel. Improves moderate protection for trout in the Tukituki River at Red Bridge (Waimarama Rd). Water quality limits for nitrate means current land use could intensify but it is hindered through a lack of irrigation water.
Option B: High protection for trout in the lower Tukituki, matching protection for long fin eel. River nitrate concentrations are managed to limit periphyton (algae and slime) growth, which means a significant reduction of nitrogen is required, leading to reduced stock numbers or changes in land use.
Option C: Existing surface and groundwater irrigators choose to stay with their existing water supplies. Allocation limits and minimum flows are the same as Option B. Water quality limits are the same as Option A but with irrigation water available from storage dams, further development of land can occur.
Option D: All existing surface and groundwater irrigators use water from storage dams which means land development can go ahead with certainty. With existing irrigators no longer taking from ground and surface water, the flows in the Tukituki River are increased over the mid to low flow range.