That independent review will allow British Columbia to "reassert its authority" over the assessment of the controversial Enbridge (TSX: ENB) pipeline, power that Dix says the provincial Liberal government has turned over to the federal cabinet.
"If we do nothing, then the decision of the B.C. government will be made by [Prime Minister] Stephen Harper," he told reporters Wednesday.
"I don't think that's acceptable to British Columbians. I think the people of B.C. want to have a voice in that process and we intend to provide that."
The panel reviewing the project jointly represents the National Energy Board and the Canadian Environmental Assessment Authority.
More than 4,000 people and groups have asked to make oral submissions at the panel review.
The panel has been holding hearings across Alberta and B.C., and has heard oral evidence from 16 B.C. communities since January.
The panel will be hearing from more people in Victoria, Vancouver and Kelowna early next year, and the hearings are expected to wrap up next April with a report due by the end of 2013.
One month after the hearings end, British Columbians will go to the polls in a provincial election.
Dix's opposition to the Northern Gateway project was outlined in a letter submitted to the Joint Review Panel in April.
He reiterated his position on Wednesday, prompting B.C. Aboriginal Relations Minister Mary Polak to question the credibility of the kind of review Dix proposes.
"One would think maybe (Dix) should have announced (the review) prior to (the NDP) taking a position on the pipeline because, of course, for a review to be seen as fair and to be seen as unbiased, you need...not to have already taken a position saying you will absolutely oppose the project," she said in an interview.
"Even if you could put in place processes that protect the environmental review from the political opinion...the perception of bias in the international community around investment would be present simply because he's already come out and said there is absolutely no way he's going to support this."
The NDP could not say how much a separate review process would cost.
Dix acknowledged there would be cost to taxpayers, but he said there is a lot more at stake financially and environmentally for the province.
Dix acknowledged the federal government ultimately has primary jurisdiction over the fate of the 1,170-kilometre pipeline that would transport oil sands diluted bitumen from Alberta to Kitimat for shipping by tanker to Asian markets.
"We have to have an environmental review and have our own certification process in British Columbia," he said.
"What the federal government does at that point, given that they've accepted we have some of the jurisdiction, remains to be seen, but we're going to assert our jurisdiction."
In June 2010, the provincial and federal governments signed an agreement that allows either party to withdraw from any National Energy Board environmental assessment of a project upon giving 30 days' notice.
Dix, who was joined by NDP environmental critic Rob Fleming and constitutional lawyer Murray Rankin on Wednesday, said he would serve Ottawa the notice within a week in office.
But when asked whether the outcome of a provincial environmental review can have the authority to block the project, both Dix and Rankin said it is a matter that a legal team is going to examine.
"The primary jurisdiction for an inter-provincial pipeline is federal," Rankin said.
"That does not mean, however, there isn't a number of provincial powers that can come to play in a circumstance like this. A team of constitutional lawyers right now is trying to analyze just what that would mean."
A spokesman for federal Environment Minister Peter Kent said Kent will not comment on hypotheticals.
Environmental advocates say they support Dix's decision, particularly when the federal government recently implemented budget cuts to the Department of Fisheries and Oceans.
“The federal budget bill earlier this year gutted the whole federal environmental process, basically paving the road for pipelines and tankers,” said Karen Wristen of Living Oceans Society in a written statement.
“The province of B.C. is more than justified in pulling out of the joint assessment agreement, because the federal process is no longer anything we could call ‘equivalent’ to proper environmental assessment. We will be pushing for a review that looks at the real risks that B.C. communities are asked to bear by the Enbridge proposal.”
Dix said he does not expect his proposal will result in strained relations with Ottawa.
"It's my intention to have a business-like relationship with whoever is prime minister, whether that's Mr. Harper or Mr. (Thomas) Mulcair," he said.
"That doesn't mean we're going to accept everything the federal government says on every issue."
Last year, a proposal by Taseko Mines (TSX:TKO) to build an open pit gold-copper mine near Williams Lake was rejected by a federal governmental review, even though the project was approved by the B.C. government.
The Canadian Environmental Assessment Agency said the New Prosperity mine proposal did not address fundamental issues central to environmental assessment, such as water quality and fish habitat.
Ottawa has agreed to hear a second environmental review after Taseko reworks the project.
Dix did not elaborate either on what the NDP would do if the proposed provincial review concludes that the Northern Gateway project should go ahead.
"I don't think you set up an independent process to assume the result," he said.
"They're going to review it independently, they're going to hear from British Columbians, and they're going to issue a report. As a British Columbian myself with strong views on (the pipeline,) I'd have to take that into consideration.
"My position now is I don't think it's in the economic and environmental interest of B.C."