The Waranga Dam is a major earthfill embankment dam with an uncontrolled spillway located approximately 150 kilometres (93 mi) north of Melbourne in the North Central region of the Australian state of Victoria. The impounded off-stream reservoir is Waranga Basin and forms part of the Goulburn River irrigation system, irrigating an area of 626 square kilometres (242 sq mi). The dam and reservoir are located in Shire of Campaspe near the City of Greater Shepparton and is located 8 kilometres (5 mi) north-east of Rushworth, 12 kilometres (7.5 mi) south-west of Tatura, and near Murchison. When full, the reservoir covers an area of 58.5 square kilometres (22.6 sq mi).

The area now covered by the Waranga Basin includes a swamp that was known as Warranga (an indigenous word) or Gunn's after William Gunn, one of the early pastoralists who established his squatting run, also called Waranga, in the area surrounding the swamp. William Gunn was a Braehour Gunn who emigrated to Victoria in 1853 from Wick, Scotland. His half-brother was the Honourable Donald Gunn of Manitoba, Canada. Gold was discovered near Waranga Swamp in 1853, making it one of Victoria's oldest goldfields.

Construction of the earth dam began in 1905 and was completed in 1915 using picks, shovels and horse-drawn scoops. The site of the basin was a former swamp in the then Waranga Shire. Construction of the dam was commissioned by the State Rivers and Water Supply Commission of Victoria for the irrigation of the Western Goulburn Valley. At the time of construction, the Waranga Basin embankment was described as the largest project of its sort in the world with an embankment height of 8.8 metres (29 ft) and length of 7 kilometres (4.3 mi).

Between 1915 and 1926, the embankment was raised in stages and a core wall was inserted. By 1921, the embankment was raised to 12.2 metres (40 ft) allowing the storage capacity to be increased to 432,360 ML (95.11 billion imp gal; 114.22 billion US gal), its current capacity. The major road between Tatura and Rushworth crosses the outlet.

Waranga Basin stores water flowing downstream from Lake Eildon as well as having a catchment area of its own. Waranga Basin supplies water to the Central Goulburn Irrigation Area and Rochester Irrigation Area. However, the Waranga Western Channel takes some of the water 180 kilometres (110 mi) to Pyramid Hill and Boort. Goulburn–Murray Water is responsible for regulating the flow of water from the basin.

Normally, only about three-quarters of the 432,360 ML (95.11 billion imp gal; 114.22 billion US gal) can be used in irrigation. However, in 2002–03, an additional 90,000 ML (20 billion imp gal; 24 billion US gal) were pumped to the Goulburn Irrigation System to assist farmers experiencing severe drought.

• Irrigation in Australia
• List of reservoirs and dams in Victoria

• Goulburn Murray Water page on Waranga Basin
• Waranga Basin Pumping