Change is a constant at Cairn Curran Reservoir.
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The storage, about 30km south-west of Bendigo, was constructed in the 1950s 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.
In October, Cairn Curran received just 1260 megalitres of inflows. Two years before it received 148,000 Ml of inflows during October.
The 147,000 Ml storage therefore 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.
Managing the highs and lows
Ensuring the storage functions safely and efficiently amid such fluctuating conditions is no easy task.
Goulburn-Murray Water senior storage officer Adrian Pearse said the rapid change between dry conditions and dramatic inflows created its own unique set of challenges.
“Because of its changeability, we look to be particularly proactive in how we manage Cairn Curran,” Mr Pearse said.
“Due to the climate and how quickly the catchment reacts to different conditions, water levels at the storage can rise and fall very quickly.
“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.
“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.
“Monitoring the reservoir for any changes to ensure its safety is also crucial following increased inflows and is something we are always very vigilant in.”
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 8000 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 September 4, 1947.
A few months into the works, officials from the Goulburn and Waranga Waters Users United League inspected the construction work and came away with mixed impressions.
The Weekly Times reported that the officials were “struck by the keenness of the staff and field workers but obtained an overall impression of limitless time and no indication of any real sense of urgency”.
The lack of urgency was likely initially due to a shortage in materials that plagued the works.
However, progress took another hit just over a year into the project, when there was a worker strike following the dismissal of one of the truck drivers.
The strike ended three days later when the truck driver was reinstated.
At other times, morale was buoyed by some of the workers’ antics.
Most notable was when a few months after the strike, 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 (about 18km) in a wheelbarrow.
The wheelbarrow had collection boxes attached to the sides to help fundraise for the hospital in Maldon, with the township having grown significantly since workers on the reservoir had moved to the area to complete the project.
Despite the enthusiasm of many of the staff, cuts to government loan funds would see works on Cairn Curran dry up and then stopped 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 April 27, 1956.
Such was the significance of Cairn Curran to the area, Maldon Shire Council announced a ‘half-holiday’ to celebrate the reservoir’s completion.
Three years later, Tullaroop Reservoir would be constructed about 10km east of Cairn Curran, ensuring further reliability for the Loddon catchment.
– Klaus Nannestad, G-MW.