The Supreme Court has dismissed a Djab Wurrung woman's fight for declarations to protect what she says are culturally significant trees threatened by a highway duplication in western Victoria.

Marjorie Thorpe argued that the state government's plans to duplicate a section of the Western Highway between Ararat and Buangor threatened culturally significant trees.

A stop-work order was put in place in December last year ahead of a trial, which was expected to run earlier this year. 

At a delayed hearing in May, lawyers for the state told the court they would no longer rely on a cultural heritage report approved by the relevant indigenous body in 2013.

The assessment, which was conducted by VicRoads and approved by the relevant registered Aboriginal part of the time, Martang Pty Ltd, was central to Ms Thorpe's legal fight.

The lawyers argued that given the state was no longer relying on the 2013 plan, there was no longer a threat of harm to Aboriginal cultural heritage and that the action should be dismissed.

Supreme Court Justice Jactina Forbes dismissed Ms Thorpe's claims and granted the state government's lawyers application to dismiss her remaining claims.

Ms Thorpe has been contacted for comment.

A long battle 

Aboriginal people and supporters began protesting on the ground to stop construction work in June 2018 and set up the Djab Wurrung Heritage Protection Embassy, which has taken legal action to stop work at state and federal levels.

Long-standing tensions over the project came to a head in October when a tree was felled that some people said was culturally significant.

Dozens of people were arrested by police.

The latest legal dismissal comes amid a third Federal Court appeal regarding the highway duplication, and a lost Supreme Court fight from a landowner that also sought to protect the trees.

But Justice Forbes's decision to dismiss Ms Thorpe's claims does not mean construction can recommence.

The ABC understands that the state government will first need to have a new cultural heritage assessment approved by the existing registered Aboriginal party for the region, Eastern Maar Aboriginal Corporation.

A government spokesperson confirmed that work on that process was underway.

"We have commenced preparation of a new Cultural Heritage Management Plan for the remainder of works on the Western Highway Duplication Project," the spokesperson said.

The ABC understands the new heritage plan is expected to be completed by the middle of next year.

The Eastern Maar Aboriginal Corporation has been contacted for comment.