Traditional owners in Western Australia are set to launch a class action lawsuit against the State Government over the deregistration of sacred Indigenous sites.

In the past year several culturally significant sites, including waterways in the Mid West, have had their protection withdrawn by the Government on the basis they no longer fit the definition of a sacred site.

Minister for Aboriginal Affairs Peter Collier told Parliament late last year that for a place to be considered a sacred site, it must show it was devoted to religious use rather than just be a place of mythological story, song or belief.

The decision to deregister several sites was sparked by development applications from mining and exploration companies.

Aboriginal Heritage Action Alliance (AHAA) co-founder Clayton Lewis said they were waiting for a Supreme Court judgement on a test case challenging the deregistration of sites in Port Hedland.

"If the ruling on Port Hedland is overturned, this opens the door for lots of other Aboriginal people to get together to have a class action against the State Government," he said.

Mr Lewis is a Widi traditional owner from the Perenjori region, in the state's Mid West, north of Perth.

He was recently notified by the Department of Aboriginal Affairs (DAA) that the Mongers Lake Waterways would be removed from state's Heritage Register, despite being recognised as a significant site in 2005.

"Under the original DAA registration it was recorded as a mythological site of significance," he said.

"The disturbance of any serpent [Beemarra] mythology upsets the balance of [the] region. We believe that the waterways should be left alone."

Mining application prompts reconsideration of site

In a statement, the DAA said the site was reconsidered after receiving an application by Perangery Pastoral Company to extract gypsum from the salt lake.

"It was determined the information available did not support that the entire water system of the lake was a single sacred site on the basis," it said.

The Widi mob was informed by a letter from the DAA that the site no longer fit the definition of a sacred site and they must prove its validity for it to remain protected.

"For this place to be determined as sacred site ... specific details regarding the religious activity conducted and are solely associated with this place would need to be provided ... rather than just a belief or the presence of an ancestral being," the letter stated.

Mr Lewis described the requirement as "ludicrous".

"It's just ridiculous to suggest that religious activity is conducted at an Aboriginal mythological site," he said.

"It's not like we are going to church on a Sunday morning there in a western sense. That's not what happens at the mythological site. We greet the Beemarra and throw sand into water, it's a cultural practise."

Lawyer Greg McIntyre, who represented Eddie Mabo in the historic 1992 native title case, is representing the Port Hedland claimants in the test case.

He has previously argued whether or not a site has been used for religious purposes was irrelevant.

Mr McIntyre confirmed he would be involved in a potential class action but could not comment further until the judgement on the Port Hedland case was handed down in a number of weeks.

The AHAA is hoping to locate any other sacred sites that have been deregistered on the basis they were not religious.

"We are hoping to bring people together and consolidate action against the state. AHAA are looking to gain an understanding of where else this is happening across the state, we already know of a number of other sites," Mr Lewis said.

The Department of Aboriginal Affairs said the group was entitled to pursue legal action.