Johnston's Sawmill Steam Plant, Steam plant remnants in Mount Molloy, Australia

Johnston's Sawmill Steam Plant in Mount Molloy is a collection of early 20th-century steam machinery remnants standing at the intersection of Santowski Crescent and Peninsular Development Road. The site includes a brick-encased Stirling water tube boiler, a Marshall steam engine, and a Walkers steam winch.

The plant was built in 1914 and operated until 1963, supporting local timber production. It emerged during a time when the region was recovering from copper mining decline and needed employment in new industries.

The machinery reflects how workers in this region relied on steam power for daily labor. It stands as evidence of how vital timber processing was to the local community.

The site sits on elevated ground at the corner of Santowski Crescent and Peninsular Development Road, making it easy to spot from the street. The location is openly accessible and requires no special preparations to explore the machinery from the outside.

Most sawmill machinery was sold, relocated and reused when a mill closed, which is why relics are scarce at old sawmill sites. Here the boiler, Marshall engine, Walkers winch and blow-down tank stayed in place, and the plant was added to the Queensland Heritage Register on 15 July 2011.