Country Australia Status Operational Type of dam Embankment dam Inflow source O'Shannassy River Operator Melbourne Water Impound O'Shannassy River | Purpose Water supply Opening date 1928 Catchment area 119 km² Primary outflow O'Shannassy River Construction began 1922 Spillway 1 | |
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Location McMahons Creek, Victoria | ||
The O'Shannassy Reservoir is an Australian man-made water supply dammed reservoir. The 3.1-gigalitre (680,000,000 imp gal; 820,000,000 US gal) water store across the O'Shannassy River is located near the locality of McMahons Creek, approximately 80 kilometres (50 mi) east of Melbourne, Victoria. The dam that creates the impoundment is called the O'Shannassy Dam.
Contents
Map of Oshannassy Reservoir, Mcmahons Creek VIC 3799, Australia
Location and features
The reservoir is part of Melbourne's water supply system. Water flows under gravity to Silvan Reservoir, then to storage and distribution reservoirs around Melbourne. It is the smallest of the water storage reservoirs managed by Melbourne Water, with a capacity of approximately 3.1 gigalitres (680,000,000 imp gal; 820,000,000 US gal), but it is on a very productive catchment, with stream flow averaging 80 gigalitres (1.8×1010 imp gal; 2.1×1010 US gal) per annum.
The location was selected as it is at sufficient altitude for gravity supply to the elevated eastern suburbs of Melbourne. A diversion weir on the O'Shannassy River and aqueduct to the Surrey Hills Reservoir in Melbourne were completed in 1914. The weir was replaced by the reservoir in 1928. The construction of the Yarra-Silvan conduits in the 1950s resulted in reduced requirements for the aqueduct and it was decommissioned in 1997.