The 3.123 GL (687 million imp gal; 825 million 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.

[3][4] The reservoir is part of Melbourne's water supply system.

[5][6][7][8] 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 construction of the Yarra-Silvan conduits in the 1950s resulted in reduced requirements for the aqueduct which was decommissioned in 1997.