1.2 Unregulated river
The volume of water stored in unregulated and regulated river channels could not be quantified in a way that is complete, neutral and free from material error.
The following figure shows a map of regulated and unregulated rivers in the Melbourne region, which are as follows:
- Yarra River and Bunyip River are unregulated rivers
- Maribyrnong River is regulated along Jacksons Creek downstream of Rosslyne Reservoir. Deep Creek is unregulated upstream of its confluence with the Maribyrnong River
- Werribee River is regulated downstream of the point where releases from Pykes Creek Reservoir enters the river. Tributaries of the Werribee River, Lerderderg River, Pyrites Creek, and Djerriwarrh Creek are all unregulated upstream of the storages.
Regulated and unregulated river channels in the Melbourne region
Water is diverted from regulated and unregulated river channels under licensed water access entitlements. Volumes diverted during the 2012–13 year are reported at 17.7 Entitled diversion of non-allocated surface water to users and 17.11 Entitled diversion of allocated surface water to users.
To estimate the volume of water stored in river channels, a detailed understanding of channel widths and surveyed water level–depth relationships is required. While the stream gauge network throughout the region is adequate to monitor flows, it is not adequate to provide a reliable estimate of river channel volume; therefore, this volume is unavailable. The volume of water stored in regulated and unregulated channels at the start and end of the 2012–13 year is expected to be significant.