WA Environment Minister Albert Jacob has ordered an external review of the Environmental Protection Authority in the wake of a Supreme Court decision declaring its environmental approvals for the Roe 8 project invalid.

But the Minister insists the agency still has his full confidence, despite WA Chief Justice Wayne Martin finding the agency failed to follow its own policies.

"I'm taking on board the lessons from the Chief Justice's ruling," he said.

"I have already had a discussion with the chair of the EPA, I am also calling for a third-party health check of the EPA.

"A thorough health check from some outside expertise, both on the legal application of Part 4 of the Environmental Protection Act, on all of the EPA's policies, but also a governance health check.

"It is crucial that the community and proponents are able to have faith in the operations of what is the state's primary environmental regulator."

The Roe 8 extension is the first stage of a planned $1.6 billion heavy haulage byway dubbed the Perth Freight Link, which the Government wants to build to connect Perth's eastern industrial suburbs to Fremantle Port.

It involves extending Roe Highway to Stock Road, but Premier Colin Barnett has already shelved the second stage of the project extending into Fremantle and the port itself.

The continuing fallout over the Roe 8 decision overshadowed the Government's planned announcement of its long-awaited strategic planning framework to streamline environmental approvals for development and expanded conservation areas across the metropolitan area.

Instead, the Environment Minister was forced to weather a barrage of questions over the EPA's handling of the already divisive proposed extension of Roe Highway across the Beeliar Wetlands.

Mr Jacob acknowledged the Chief Justice found no evidence the EPA had considered its policies when approving Roe 8, but the Minister told reporters the EPA board "assured" him those policies were, in fact, considered.

"I'm saying they have assured me that they did consider their policies," he said.

"I'm not saying whether they were followed to the absolute nth degree, but that have assured me that they did consider them."

Minister keeps faith with EPA despite audit

Under further questioning, Mr Jacob conceded the EPA's Assessment Report contained no evidence or indication of any such consideration.

"I am disappointed at the documentation level which has gone into this and I have already spoken to the chair about that, and that's one of the reasons why I'm calling for this health check," he said.

Having accepted the EPA's assurance, the Minister struggled to respond to questions about whether he had asked a single question of the EPA on how, when or in what manner those policies had been considered.

"You have faith, as a Minister for Environment, that the Environment Protection Authority is doing due diligence on their governance," he said.

But the Minister rejected suggestions that an external review indicated a lack of confidence in the agency.

"I have full confidence in the EPA," he said.

He said he had not queried the current board about its assurance after the court decision, saying many on the board who granted the project's approval were no longer there.

With the appointment of a new chair and board members, and with the Supreme Court decision, the Minister said it was an "ideal time" to review the operations and governance organisation.

The State Government had been expected to award contracts for the first stage of the road project as early as this week.

But the timing, if not the future, of the project has been thrown into doubt.

Wetlands protesters vow to take Roe 8 fight to election

Roe 8 protesters hand back move on notice to Government outside WA Parliament House. ( ABC News: Jessica Strutt )

Residents, environmentalists and Aboriginal groups have condemned the project for damaging a sensitive bushland and wetland area.

The transport industry had severely criticised the government for putting off the second stage of the project, saying building only Roe 8 would create a road to nowhere.

The State Opposition and Greens have called on the Government to abandon the project altogether.

Opposition Leader Mark McGowan believes the EPA's flawed process was the product of political pressure.

"I think the EPA has acted here in the way that they have, because of the pressure from the Government to approve this project," he said.

"And this project was flawed from the very beginning,.

"The court knows it, the community knows it, the only person who doesn't know it is Colin Barnett."

Thousands have attended anti-Roe 8 rallies in recent months and drilling was disrupted by protesters when it began last month.

Protesters this morning vowed to make the Roe 8 extension an election issue, with the timeframe of the project now potentially blowing out within the vicinity of the next state election in March 2017.

Roe 8 opponents say there is profound community opposition to the project, and the Government had no democratic mandate to continue with it.

Delay will incur increased costs: Premier

Mr Barnett remains committed to pushing ahead with the project, even if it means a new environmental approvals process.

But he said that will cost time and money.

"The impact of that decision is delay, significant increase in cost and a loss of jobs that would have been available for the community," he said.

"So I think it's a very regrettable situation that we face."

Mr Barnett said he understood the concerns of opponents of Roe 8 and the need to protect an important environmental area.

But he said the Government had to consider issues other than just the environment.

"That is the job of the EPA ... from a State Government point of view our responsibility goes beyond the environment, significantly beyond the environment."