EXHIBIT 99.4
Media Release
Rio Tinto and WA Government partner to expand Dampier Seawater Desalination Plant
04 March 2026
Rio Tinto and the Western Australian Government have entered into a 50:50 joint venture to complete both Stage 1 and Stage 2 of the Dampier Seawater Desalination Plant.
Once fully operational, the plant will deliver 8GL of desalinated water per year to the West Pilbara Water Supply Scheme, reducing pressure on regional aquifers.
The West Pilbara Water Supply Scheme is operated by Water Corporation and supplies the towns of Karratha, Wickham, Dampier, Roebourne, Point Samson and the industrial areas of Cape Lambert and the Burrup Peninsula.
Construction of Stage 1 of the desalination plant is underway and is expected to begin delivering 4GL of annual desalination capacity later this year.
Stage 2 construction, which will add a further 4GL of annual capacity, has commenced, with first water expected in 2027.
Together, Stages 1 and 2 will significantly reduce abstraction from the Bungaroo and Millstream aquifers.
The joint venture builds on a 2025 Memorandum of Understanding, under which the WA Government and Rio Tinto agreed to work together to strengthen water security in the Pilbara.
Over the past five years, the West Pilbara has frequently experienced annual rainfall and streamflow below the long-term average. This has reduced important groundwater recharge at the Millstream and Bungaroo aquifers, which supply the West Pilbara Water Supply Scheme.
Abstraction from these groundwater sources is of significant concern to Traditional Owner groups.
The A$1.1 billion Dampier Seawater Desalination Plant, which will be operated by Rio Tinto, will considerably reduce groundwater take and help protect sites of environmental and cultural importance.
Western Australian Premier Roger Cook said: “Western Australia has the strongest economy in the nation thanks largely to the Pilbara and our world-leading resources industry. That’s why we want to ensure the Western Australians who live in such an important part of our State have access to the quality infrastructure and services they deserve.
“We already working with Yindjibarndi Aboriginal Corporation to improve the Millstream aquifer’s sustainability. Now, we are investing hundreds of millions of dollars in a project that will deliver billions of litres of water to local households and businesses. This project shows why our government’s Made in WA plan is so important to our State’s future and how it is helping deliver our priorities.”
Rio Tinto Iron Ore Chief Executive Matthew Holcz said: “We understand water is a scarce resource, especially in the Pilbara. Bringing on the Dampier Seawater Desalination Plant is an important step as we work to reduce our reliance on groundwater abstraction.
“Stage 1 of the Dampier Seawater Desalination Plant will reduce our draw on the Bungaroo aquifer, which we recognise is deeply important to the Robe River Kuruma People. We are pleased to partner with the Western Australian Government to improve the security and sustainability of water supply throughout the Pilbara.”
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