It’s usually only during floods and droughts that the everyday modern person thinks at all about the availability of water; we take for granted the trickle from the tap. But the contrast between the recent dry spell of many months and the rain of the last week has prompted Goulburn-Murray Water, the entity that manages the storage and delivery of water in our region, to share some information about how these extremes are managed. It is perhaps more interesting than you would think.

Flow and fluctuations

Cairn Curran Reservoir was constructed between 1947 and 1956 to try and provide a semblance of reliability to one of Victoria’s least reliable rivers: the Loddon. The Loddon River’s changeability is evident in the past few years alone; last month, Cairn Curran received just 1,260 megaliters (ML) of inflows compared to 148,000ML of inflows during October 2022. Thus, the 147,000ML storage went from receiving more than its entire capacity in one month in 2022, to less than one-thousandth of its capacity in the same month just two years later.

Without Cairn Curran, the full effect of these extremes would be felt; in the dry times, irrigators would have little more than a trickle of water along the Loddon River to draw from, and during floods, the most extreme flows would rush downstream without a buffer.

This means that the reservoir needs to be proactively managed. Goulburn- Murray Water (GMW) Senior Storage Officer Adrian Pearse said the rapid change between dry conditions and dramatic inflows created its own unique set of challenges. “When the storage is low, we need to keep the foreshore clear of debris and rubbish, because if we get some rain and it fills up, what’s left on the foreshore will be dragged into the storage,” he said. “There’s a lot of red gum trees around Cairn Curran that often lose large branches when conditions go from dry to wet, so we need to be particularly vigilant in removing any logs that could get stuck in the radial gates.

Construction of Cairn Curran

The reservoir was built to not only handle such extremes but to moderate them as well. Soon after the region was settled it became clear that the Loddon River’s unreliability was a major obstacle. In 1948, the Shepparton Advertiser described irrigation on the Loddon River as being ‘a story of undue optimism and disappointing results’. At the time, the only water storage on the Loddon River was Laanecoorie Reservoir, which had a modest capacity of 8,000 ML. While irrigators had been advocating for an additional storage on the river since the Great Depression, the Second World War meant construction of Cairn Curran would not begin until 4 September 1947.

A shortage in materials initially plagued the works and a worker strike following the dismissal of a truck driver also delayed progress. At other times, morale was buoyed by workers’ antics. Most notable was when Jack Baxter, another truck driver working at the reservoir, placed a 10-pound wager that he could push Maldon publican Frank O’Brien from Castlemaine to Maldon in a wheelbarrow. The wheelbarrow had collection boxes attached to the sides to help fundraise for the hospital in Maldon.

Cuts to government loan funds meant that works on Cairn Curran dried up altogether in 1952. For about two years, the reservoir remained untouched in a half-finished state. However, in 1954, following a change in government, funding was allocated to complete Cairn Curran and works on the storage recommenced. This time, the works went smoothly, with the storage officially opening on 27 April 1956. Such was the significance of Cairn Curran to the area, Maldon Shire Council announced a ‘half-holiday’ to celebrate the reservoir’s completion.

It’s not clear why we no longer observe this half-holiday, but it is clear that Cairn Curran serves a vital purpose to the district amidst an inconstant climate. 

This article appeared in the Tarrangower Times, 6 December 2024.