Julius dam: A vital outback water source celebrates 50 years

Five years later, Julius Dam was completed approximately 70 kilometers northeast of Mount Isa, at the confluence of the Leichhardt River and Paroo Creek, to address this critical need.

Construction, undertaken by Thiess Brothers, involved a significant workforce, including laborers from Scotland, England, and Ireland, many of whom resided on-site with their families. The remote location presented considerable engineering challenges.

Engineers opted for a unique concrete multiple-arch and buttress design to minimize material usage while ensuring structural integrity. Sunwater, the current operator, explains this choice was crucial due to the logistical difficulties of transporting materials to the remote site. “Because of its remoteness, because of the difficulty of getting materials in, that’s the reason they decided to go with that structure,” stated north region general manager of operations, William Weaver. This design remains the only one of its kind in Queensland.

University of Queensland geotechnical engineering professor Alexander Scheuermann noted the dam’s unusual design. “The first thing I thought when I saw the dam was, ‘Where’s the spillway?’” Instead of a separate spillway, the dam’s 18-meter-wide concrete arches allow excess water to flow directly over the structure, preventing damage.

Julius Dam boasts a capacity of 107,500 megalitres, roughly equivalent to one-fifth of Sydney Harbour’s volume. Initially intended to supplement Mount Isa’s water supply, its role has expanded considerably.

The 113-kilometer North West Queensland Water Pipeline, finished in 1998, now delivers water to mining operations like the Ernest Henry copper and gold mine near Cloncurry. A further 38-kilometer pipeline, added in 2010 after a drought, provides Cloncurry with a consistent year-round water supply. Lake Moondarra remains the primary water source for Mount Isa, with Julius Dam serving as a crucial backup.

Despite the region’s susceptibility to prolonged dry periods, Julius Dam has reportedly spilled annually for the past decade. William Weaver attributes this reliability to regular replenishment from seasonal monsoonal and cyclonic rainfall. “What Lake Julius does is it gives you that real assurance and real surety of supply,” he said.

Looking ahead, Professor Scheuermann emphasizes the importance of ongoing maintenance to ensure the dam’s longevity. He notes that while dams can operate for over a century, evolving climate patterns and increased water demand require careful assessment. A dedicated team of seven based in Cloncurry manages the dam and its pipelines.

“It’s one of those little hidden gems that most people don’t even know exists because it’s tucked away in the middle of nowhere,” Weaver concluded, highlighting the dam’s understated but vital contribution to the region.