Traditional Owners are concerned the site of Western Australia's Argyle diamond mine will be returned to them by Rio Tinto without the company meeting agreed rehabilitation criteria.

The company's defunct site in East Kimberley once produced 90 per cent of the world's pink diamonds before ceasing production after nearly 40 years in November 2020.

Rio Tinto said it was on track to finish demolition, landforming and revegetation this year, before returning the land to its Miriwoong and Gija Traditional Owners, after which a 10-year monitoring and maintenance program begins.

Gija woman and Gelganyem Limited - which manages relations between Rio and TOs - said the site's current state was unacceptable.

Gelganyem Limited chair Kia Dowell said Traditional Owners were concerned with current standards in the rehabilitation plan and confirmed they would not accept return of the land if it remained permanently contaminated.

"We are simply asking - just like I do with my children - if you make a mess, you clean it up," Ms Dowell told the ABC.

"We want the accountability to sit with the accountable parties who have extracted so much value from this site.

"We want those profits to be reinvested into the Country to ensure that my kids, their kids and so on can go to that Country and interact with it the way that their ancestors used to be able to."

In December, Ms Dowell told National Indigenous Times there was "zero trust" in Rio Tinto with regards to management of the site.

A Rio Tinto spokesperson told National Indigenous Times the company acknowledged Traditional Owners as custodians of Country, with a deep connection to the land.

"They have a critical role in caring for Country throughout the Argyle Diamond Mine life cycle, including closure," they said.

"We understand the impact closure has on the community and we continue to work closely with Traditional Owners on the Argyle mine closure, seeking their feedback, embedding their perspectives, and ensuring cultural authority is respected throughout the process."

The spokesperson said the company would continue working with Traditional Owners to develop a co-managed cultural heritage management plan.

"This will set out how cultural heritage sites and values will be managed and monitored through shared decision-making, and support progress towards closure outcomes that Traditional Owners have identified," they said.

"Our priority is to deliver a safe, stable and culturally respectful closure that recognises Traditional Owners' deep connection to Country, while ensuring the site's long-term environmental outcomes are actively monitored and managed.

"We will continue monitoring surface and groundwater for at least 10 years, alongside annual fish sampling at Gap Dam, Limestone Creek and Flying Fox Creek, to support safe fish consumption under Australian government guidance."

The WA government requires comprehensive, documented Traditional Owner engagement to be included in the mine closure plan.