Hume dam (1936) and Snowy Mountains scheme (1950s/60s) add to South Australian concerns about salinity

South Australia was initially excluded from negotiations over effects of the Snowy Mountains scheme on the River Murray basin.
Image courtesy Create Digital

The Hume Dam, the largest water storage in the southern hemisphere, was completed in 1936 near Albury, New South Wales, at the junction of the upper Murray and Mitta Mitta rivers.

The dam and its reservoir was part of the 1920s River Murray Water Agreement between the federal, New South Wales, Victorian and South Australian governments. Its size of 1,250,000 acre feet had been authorized under the 1934 amendment to the agreement, allowing for later enlargement to 2,000,000,000 acre feet (2500 GL/gigalitres).

To compensate for the enlarged Hume dam, the locks along the Murray were cut back from the original 59 to 13 and South Australia got funding for its barrages at the Murray mouth.

The enlargement of Hume dam to 2500GL capacity was agreed to in 1945. But this was year after the Morgan-Whyalla pipeline had been completed and work on a pipeline from Mannum, bringing Adelaide’s first Murray water supply, was only a few years away.

South Australia’s extra reliance on the River Murray was not only concerned with flow coming down the from eastern states but also a growing problem of salinity. This problem intensified with the Snowy Mountains Electricity Scheme in New South Wales in the 1950s and 1960s, diverting water west into the Murray Darling system.

But South Australia, initially excluded by the commonwealth and two other states from negotiations over the project, wasn’t convinced that it would benefit. It was also opposed to New South Wales's proposal that it supply South Australia’s water entitlement from the River Darling, with its higher turbidity and salinity, rather than Hume Dam that was fed by the high-quality snow melt from the Snowy Mountains. Nor was South Australia happy about the plan to link the Geehi catchment, feeding into the Hume Dam and the Murray, to the Tumut catchment that supplied the expanding Murrumbidgee irrigation areas.

A new agreement saw the transfer of Murray water into Murrumbidgee irrigation stopped and South Australia getting its share of diverted Snowy River water. But the experience, and continued growth of irrigation in New South Wales and Victoria, prompted South Australia premier Tom Playford to come up with his own independence plan: the Chowilla Dam on the River Murray.