The Julius Dam is a multiple-arch concrete-buttress dam across the Leichhardt River and Paroo Creek, located north-east of Mount Isa, in north-west Queensland, Australia. Completed in 1976, the impounded reservoir, Lake Julius, supplies water for irrigation and potable town water for Mount Isa and . The dam was named in honour of former Mount Isa Mines chairman and director Julius Kruttschnitt, who was instrumental in helping establish the mining industry in the region.
The dam is unique in Queensland and is a concrete multiple arch and buttress type structure, with the uncontrolled spillway discharging over the crest of twelve arches. An additional three arches, located on each side of the spillway, approximately higher than the crest, provide overflow in times of maximum flooding. The spillway is a precast superstructure and the dissipation slab at ground level is post tensioned to the foundation rock. The crest is above bed level at . The twelve arch barrels, founded on a triangular arch base, are constructed in independent arch rings and are hinged at buttress springing lines.
The dam wall is high, long, and holds back of water storage at full capacity. The resultant reservoir covers a surface area of with an average depth of , drawn from a catchment area of .
Operational volumes at the dam have ranged between a low of 59.22%, recorded on 24 November 2014, and a high of 169.73%, recorded on 15 January 2004; with the latter due to record-breaking rainfall upstream, near Mount Isa.
In 2008, SunWater announced plans to upgrade the capacity of the dam's spillway.