The volume recognised in the water accounting statements (1,007 ML) represents the volume of water taken and used against entitlements to take and use water for stock and domestic purposes in the Melbourne region.
The sum of those entitlements for the Melbourne region is 1,720 ML.
The volume does not include domestic and stock use under section 8 of the Water Act 1989 (Victoria). Section 8 provides that, in some circumstances, a person has a private right to take and use water for domestic and stock use without an entitlement and free of charge. These circumstances include the right to capture rain that falls on a roof, and the right to collect water that occurs or flows on land for domestic and stock purposes. The Water Act 1989 (Victoria) defines domestic and stock use as the ‘use of water for household purposes, the watering of animals kept as pets, the watering of cattle or other stock, fire prevention (this is limited to certain sources of water) and irrigation of a kitchen garden’. A kitchen garden is defined in the Water Act 1989 (Victoria) as a garden used solely in connection with a dwelling; its size varies depending on when the land was alienated by the Crown and whether the garden is irrigated by surface water, groundwater or both.
Domestic and stock use excludes use for intensive or commercial use such as dairies or piggeries, or irrigation of a garden from which produce is sold.
The following table shows information on licences to divert water from unregulated rivers for domestic and stock purposes in the four river basins within the Melbourne region.
| Catchment | Licensed volume – for take and use in unregulated rivers (ML) | Licensed use (ML) |
|---|---|---|
| Bunyip |
652 |
652 |
| Yarra |
746 |
33 |
| Maribyrnong |
291 |
291 |
| Werribee |
31 |
31 |
| Total |
1,720 |
1,007 |
Melbourne Water supplied data for the Yarra catchment, and Southern Rural Water supplied data for the Bunyip, Maribyrnong and Werribee catchments.
Victorian Department of Sustainability and Environment.
Different methods were used to estimate diversion in different geographic parts of the Melbourne region, based on data availability.
Domestic and stock licences issued by Southern Rural Water are not metered. These licences apply to the Bunyip, Maribyrnong and Werribee catchments. Based on historical calculations, Southern Rural Water assumed that all stock and domestic use licences were fully used. That is, in the absence of any metered data, diversion volume was assumed to be equal to entitlement volume. This assumption is likely to be a source of overestimation. This assumption is appropriate for licences in the Bunyip, Maribyrnong and Werribee catchments, but not for the Yarra catchment, where some metered data were available.
Of 746 ML of stock and domestic licences issued by Melbourne Water, only 153 ML of those licences were metered. These licences apply to the Yarra catchment. In the Yarra catchment, the 746 ML of stock and domestic licences includes inactive licences, licences on small urban properties where only domestic use is occurring, and licences on rural areas where stock could use the entire licence. Of the 153 ML of metered licences, only 33 ML was recorded as usage. For the Yarra catchment, only metered use is recognised in the account. That is, in the absence of any metered data, diversion volume is assumed to be equal to 0 ML. This assumption is likely to be a source of underestimation.
Based on the estimation method outlined, the estimates of unregulated diversions should be considered to have a low level of certainty.