Opponents of a major bauxite mine in WA's South West say the state government's decision to overturn a string of proposed conditions on the project shows it is more interested in revenue than the environment.

Environment Minister Reece Whitby gave the green light to mining giant South32's expansion of its Worsley Alumina, overturning a string of potential conditions governing the project that the Environmental Protection Authority (EPA) had recommended.

Some of those conditions included significant offsets for the forests dug up to access the bauxite, and a requirement for the company to achieve net zero carbon emissions by 2050.

The document detailing the reasons behind Mr Whitby's decisions stated he agreed with the appeals committee that certain conditions should be altered.

"The minister has arrived at this decision having considered the Appeals Committee's report, and the responses to the appeal from the department and the proponent," it stated.

The decision comes after the consideration of 134 appeals, from both opponents and South32 itself, against the Environmental Protection Authority's (EPA decision) in July to give the project conditional approval.

While the project still requires state and federal approval, those involved in the process believe it is effectively a formality once this stage is reached.

Residents from the nearby communities of Boddington, Wandering and Williams, around 130km south east of Perth, had united in opposition to the proposal, and said they were disappointed by the minister's decision.

Locals for Environmental Action and Protection (LEAP) spokesperson Josie Sherlock said she thought Mr Whitby was more concerned with commerce than the environment after he rubberstamped South32's Worsley Alumina expansion. 

"From what I can see in the document, the changes that have been made have been in favour of South32," she said.

"We went to the appeals convenor with our concerns, and very little of our concerns have been addressed."

WA Forest Alliance spokesperson Jason Fowler said the original recommendations from EPA had not gone far enough, and the changes made were even worse for environmental outcomes.

"The WA forest alliance was very disappointed today by the minister's indication he will approve the proposal," he said.

Mr Fowler said the main concern were the conditions that have been removed, related to the state's regulation of the proposals greenhouse gas emissions. 

"The EPA can no longer assess impacts from greenhouse gas emissions from projects … it now falls under the federal safeguard mechanism," he said.

"Now that mechanism has been beefed up by the Albanese government, but there's nothing to say that if we have a new Liberal government next year they wouldn't gut that mechanism."

A spokesman for Mr Whitby said it would not be appropriate to comment as the project was still subject to a ministerial decision-making process.

South32 had itself appealed against the original EPA recommendations, arguing some of the conditions would create significant operating challenges for the project.

However, following Mr Whitby's decision, the bauxite mining giant has changed its tune.

In a statement released on Friday morning, a South32 spokesman said Mr Whitby's determination was a positive outcome for Worsley Alumina.

"We are pleased to advise that the minister has determined after considering available information, that the EPA's assessment and overall conclusion that the project may be implemented, subject to conditions, is reasonable," the statement read.

"Further, the minister has agreed with the Appeals Committee's recommendations to amend specific conditions based on the arguments presented during the appeals process, including by Worsley Alumina."

The spokesman also said state approval of the project by Mr Whitby was expected later this month with federal approval expected early next year.

A spokesperson for Mr Whitby could not confirm if this timeline was accurate.