A group of Hawke's Bay residents says the Ruataniwha water storage scheme is going ahead too fast and people have not been told enough about it.
A spokesperson for the Transparent Hawke's Bay group, Pauline Elliot, says the scheme is the biggest economic project in Hawke's Bay yet residents have been given so little information it's impossible for them to assess its economic and environmental risks.
She says the group's not saying the dam is not a good idea, just that ratepayers don't have enough information.
Ms Elliot says one of the big concerns was the lack of consultation and the group will ask the Environment Minister to delay the project.
The Hawke's Bay Regional Council says the business case for the water storage project is still being prepared and the council has not yet made any decision on whether it will go ahead.
It says once the business case is ready, and it has the final facts and figures, it will begin a special consultation process with the public.
Meanwhile, a commercial manager has been appointed to the scheme.
Duncan MacLeod, formerly of BNZ Bank, has been charged with explaining the benefits of the intensive agriculture to farmers.