The reservoir is formed by an earthen embankment dam across the eastern branch of the Plenty River below the junction with Jacks Creek.

Water is diverted from Wallaby and Silver Creeks, part of the Murray–Darling basin on the northern side of the Great Dividing Range—via the open, granite-lined Wallaby Aqueduct—across the Great Dividing Range just east of Mount Disappointment, then into Jacks Creek and into the reservoir.

The reservoir acts as a settling basin before the water travels 8 kilometres (5 mi) down the Clearwater Channel to Yan Yean.

[6] Grouted stone columns were installed on both the upstream and downstream sides of the dam wall in 2011.

In 1879 low dam levels showed that further water sources were necessary to meet increased demand by a growing population.