The Green Party wants the Government to pull out of the Ruataniwha water storage project and not subsidise it through the Crown Irrigation Investments company.
Hawke's Bay Regional Council says the dam is not commercially viable under the resource consents it has been issued and major investors Trustpower and Ngai Tahu have pulled out.
Greens water spokesperson Eugenie Sage said that with commercial investors dropping out, taxpayers and Hawke's Bay ratepayers will be left to front most of the cost of a $275 million construction cost that is currently not viable.
Meanwhile, four Hawke's Bay Regional Council members say they were kept in the dark about the council's latest submission to the board of inquiry into the project and it has no moral authority.
Cr Rex Graham said council officers sent a submission on Friday challenging the board's draft decision aimed at protecting the Tukituki River from nitrate pollution.
He said some of the suggestions in the submission were rejected by the council's regional planning committee last week.
Cr Graham said the councillors have written to the two ministers responsible for the board of inquiry to let them know there is an alternative view on the council.
He said that view is the draft decision should be accepted and farmers should work within the environmental constraints set by the board.
The final decision from the Board of Inquiry is now due by 28 June. Submissions on its draft decision closed on Friday.