Premier Colin Barnett has announced a $450 million plan to double the capacity of its desalination plant near Binningup, as it attempts to secure future water needs for communities stretching from the Perth metropolitan area to the Goldfields.

One of Western Australia's largest unions says a significant decline in the number of people taking up apprenticeships in the state is a clear signal for urgent government intervention.

Civil and mining contractor Brierty has been nominated as the preferred proponent for a $100 million Main Roads maintenance project in a joint venture with AECOM Australia. The Main Roads Alliance contract term is for three years.

Harvey Fresh has announced it will take on the contract to supply Coles with private label milk for its Western Australian supermarkets. The Harvey-based milk processor said the deal, which will commence in October, would elevate it to become the state's largest supplier of fresh milk.

Galaxy Resources has announced a technology licensing deal with US-based lithium ion battery producer K2 energy Solutions.