More transparency and an urgent extension to the board of inquiry's public hearing of the Ruataniwha Catchment Proposal has been called for by Labour leader David Cunliffe.
The proposal includes the Ruataniwha dam and Plan Change 6 - new rules and regulations designed to deal with water quality issues in the Tukituki River.
Mr Cunliffe met iwi stakeholders against the proposal process yesterday and said the process to date was "mysterious, dogged by coincidences, lacking in transparency and of grave concern to anybody who believes in due process".
"We should seek an urgent extension, we should ensure the full briefing," he said.
Conservation Minister Dr Nick Smith had "clearly intervened" to stop a draft document, critical of the scheme, from being submitted to the inquiry, he said.
"I also note that the Ministry for Primary Industries' submission was heavily amended between the draft and the final.
He said Dr Smith would likely lose the confidence of the Prime Minister because it appeared he had withheld the report from "a relevant statutory authority - that's a serious matter" and had not been full and frank describing his involvement. The Department of Conservation's draft report was a "very substantial and serious document" that drew attention to inconsistencies of the scheme with DoC's national policy statements on fresh water and coastal management.
"To field that the department was somehow prevented from putting that on the table for the commissioners and the board to consider I think is an outrage and I think the minister should go.
"It is essential that all of the facts are put on the table in a very open and transparent manner, so people of the Bay and New Zealand can make up their minds for themselves."
He said coincidences keep happening around the proposal.
"It is interesting that one farm will be open to access to the public site two days after the submission process closes [October 8]. It is interesting another farm mysteriously closed the day before we were due to go on."
Environmental Protection Authority general manager for applications and assessments, Sarah Gardner, said any extension to the board of inquiry's timeline was a matter for the Minister for the Environment and the Minister for Conservation.
The Hawke's Bay Regional Authority's investment company is heading the catchment proposal.
Director Andrew Newman said the timeline for submissions had been well publicised since the board of inquiry was announced in June.
"This process has been running for a while, so I don't think the deadline is a surprise to anybody."
Consenting manager Stephen Daysh said scientific information on the proposal had "been in the public domain for a very long time," with council reports posted online.
Mr Newman said disagreements over the scheme were "the nature of the process".
"I am really looking forward to the hearings process whereby this argument becomes an evidential-based one, as opposed to a media-based political exercise."
Hawke's Bay Regional Council has laid a formal complaint with Radio New Zealand over its recent reporting of the Ruataniwha Water Storage Scheme.
The council said it was concerned over the radio network's coverage of the draft Department of Conservation submission on the Ruataniwha Water Storage Scheme.
The council rejected suggestions the draft submission said the nutrient management model for the Tukituki River was "untested and risky and could kill the Tukituki River," as quoted by the station. The council also said the DoC submission did not say the dam would "poison" the river, nor would it make the river "toxic".