The creation of Lake Eildon
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- Why a Dam here? -
In considering the history of Lake Eildon and its
construction, it is first necessary to understand the choice of the site. Lake Eildon
at its present level floods a 37 kilometre long stretch of the upper Goulburn River Valley.
This valley encompasses the confluence of five major alpine rivers and their
watersheds. These river are:
· The Goulburn River
· The Delatite River
· The Jamieson River
· The Howqua River
· The Big River
· The Goulburn River
· The Delatite River
· The Jamieson River
· The Howqua River
· The Big River
Map showing Lake Eildon and its tributaries
The purpose of Lake Eildon is primarily to provide a reliable source of water for irrigation within the Murray Darling Basins southern regions. The dam discharges into the Goulburn River and, from lower down in the Goulburn, is diverted further to other storages such as The Waranga Basin and Goulburn Weir.
Lake Eildon has
a maximum capacity of 3,334,158 mega litres. This makes it the largest storage
on the Goulburn River and the second largest storage in the Southern Murray
Darling Basin, Dartmouth Reservoir being the largest.
In area, the lake covers 13,840 hectares and has a shoreline of 515 kilometres.
-Sugarloaf Resevoir-
Construction of Sugarloaf Resevoir 1918
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Lake Eildon’s construction began in 1915 with the State Rivers and Water Supply Commission, a now defunct agency, proposing the construction of a weir at the lower end of the Goulburn River Valley. The weir’s purpose was to supply a more reliable source of water for agriculture throughout drought years and irrigation schemes downstream. It also provided water for towns and cities and hydro-electricicity for the growing communties within the region. The weir was to be named Sugarloaf Reservoir and its construction would flood large tracts of the valley. This flooding included the settlements and the township of Darlingford, which had seen a rich history since the mid-19th century.
Physically, the Sugarloaf Weir was made up of a rock filled earth wall with concrete pylons, steel gates and piping to control the flow of water downstream. It was completed in 1929; however, it was in commission for less than a year when it was deemed to small and modification began to raise the height of the dam wall and weir. This trend continued, when in 1935 the wall was again raised to bring the storage capacity of the reservoir up to 377,000 mega-litres. |
-Eildon Dam-
Due to several consecutive years of drought throughout the 1930s and early 1940s, coupled with the pressures of the Second World War and its necessitated food production increase, a feasibility study was conducted. It determined the site of a new and larger dam, with longer term water storage in mind. The study concluded that the site of Sugarloaf Weir would serve well for the new dam and in 1951 work commenced on what would become the modern day Lake Eildon.
Construction works on Lake Eildon Dam Wall 1954
Eildon Dam is made up of an earth cored rock wall much like the
previous Sugarloaf Reservoir; however, to accommodate the immense increase in
height it was tiered to displace the load of the water body behind it. The dam
wall stands at 83 metres high and comprises some 10,200 cubic metres of fill,
with an overall length of 1085 metres including the spillway.
Eildon Dam’s spillway is 288 metres long and can discharge 3,356 cubic metres per second; however, the dam’s regulation, in conjunction with other storage sites, means that this is rarely seen as it would result in catastrophic flooding down steam and loss of irrigation water in an uncontrolled manner. The regulation of flows downstream for irrigation, hydro-electric power generation or environmental flows are achieved through either the use of the spillways gates or the release of water from the bottom of the dam through seven metre wide pipes, which also run the hydro-electric power station. The hydroelectric power station at Eildon Dam has a generating capacity of 150 megawatts and produces an average of 225 gigawatt hours every year. The peak electricity generation occurs throughout late spring and summer when most water is being released for irrigation. The power station is operated by AGL.
Eildon Power Station
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Eildon Dam Wall Today
Eildon Dam Spillway Discharging
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