Melbourne
17.7 Non-allocated diversions to users

The volume presented in the water accounting statements (16,883 ML) represents the volume of water diverted in the Melbourne region for irrigation, stock and domestic (stock and domestic), commercial and industrial and other surface water entitlements without prior allocation announcement.

The volume presented for irrigation does not include:

• water diverted to Melbourne retail authorities for the urban water supply system (17.12 Surface water allocation diversion: urban system)
• water diverted under High Reliability Water Shares and Low Reliability Water Shares (17.11 Surface water allocation diversion)

The following presents the licensed volume of entitlements in the Melbourne region and the volume diverted during the 2010–11 year.

Licensed entitlements and volume diverted in the Melbourne Region during 2010–11 year

		Catchment
	Class	Bunyip	Yarra	Maribyrnong	Werribee	All catchments
Licensed volume (ML)	Irrigation	17,759	20,300	3,512	2,032	43,603
	Stock and domestic	652	735	329	31	1,747
	Commercial and Industrial.	488	2,581	54	251	3,374
	Other	550	19,774	23	n/a	20,347
Total licensed volume (ML)		19,449	43,390	3,918	2,314	69,071
Metered diversions (ML)	Irrigation	1,984	3,464	300	262	6,010
	Stock and domestic	0	6	0	0	6
	Commercial and industrial	0	1,310	15	0	1,325
	Other	0	7,248	n/a	n/a	7,248
Total metered diversions (ML)		1,984	12,028	315	262	14,589
Estimated non-metered diversions (ML)	Irrigation	0	n/a	0	0	0
	Stock and domestic	652	0	305	31	988
	Commercial and industrial	488	0	17	251	756
	Other	550	n/a	n/a	n/a	550
Total estimated diversions (ML)		1,690	0	322	282	2,294
Total diversions (ML)		3,674	12,028	637	544	16,883

Melbourne Water (Yarra catchment) Southern Rural Water (Bunyip, Maribyrnong and Werribee catchments).

Victorian Department of Sustainability and Environment.

The volume presented for this item is a combination of metered diversion data and estimates of non-metered diversions.

Approximately 65% of licences in the Melbourne region are metered, as shown in the following table.

Licensed volumes and portion that were metered in the Melbourne Region during 2010–11 year

		Catchment
	Class	Bunyip	Yarra	Maribyrnong	Werribee	All catchments
Licensed volume (ML)	Irrigation	17,759	20,300	3,512	2,032	43,603
	Stock and domestic	652	735	329	31	1,747
	Commercial and Industrial	488	2,581	54	251	3,374
	Other	550	19,774	23	n/a	20,347
Total licensed volume (ML)		19449	43,390	3,918	2,314	69,071
Licensed volume that is metered (ML)	Irrigation	11,933	16,980	2,454	1,355	32,722
	Stock and domestic	0	138	0	0	138
	Commercial and industrial	0	2,365	0	0	2,365
	Other	0	13,858	n/a	n/a	13,858
Total licensed volume metered (ML)		11,933	33,341	2,454	1355	49,083
Licensed volume that is metered (% of licensed volume)	Irrigation	67%	84%	70%	67%	75%
	Stock and domestic	0%	19%	0%	0%	8%
	Commercial and industrial	0%	92%	0%	0%	70%
	Other	0%	70%	n/a	n/a	68%
Total metered portion (%)		61%	77%	63%	59%	71%

Where metered data were available, the diversion was calculated as the actual diversion for the 2010–11 year. The following table shows the portion of diversions that were metered during the 2010–11 year.

Total diversions and the portion that were metered in the Melbourne region during 2010–11 year

		Catchment
	Class	Bunyip	Yarra	Maribyrnong	Werribee	All catchments
Total diversions (ML)		3,674	12,028	637	544	16,883
Metered diversions (ML)	Irrigation	1,984	3,464	300	262	6,010
	Stock and domestic	0	6	0	0	6
	Commercial and industrial	0	1,310	15	0	1,325
	Other	0	7,248	n/a	n/a	7,248
Total metered diversions (ML)		1,984	12,028	315	262	14,589
Metered diversions (% of total diversions)	Irrigation	54%	29%	47%	48%	36%
	Stock and domestic	0%	0%	0%	0%	0%
	Commercial and industrial	0%	11%	2%	0%	8%
	Other	0%	60%	n/a	n/a	43%
Total metered diversions (% of total diversions)		54%	100%	49%	48%	86%

Where metered data were not available, the diversion was estimated using the following assumptions:

• Diversion volume was assumed to be equal to zero for licenses in the Yarra catchment (as per Melbourne water assumptions).
•  Diversion volume was assumed to be equal to the licensed entitlement volume for licences in the Bunyip, Maribyrnong and Werribee catchments (as per Southern Rural Water assumptions).

Broad assumptions have been made to estimate unmetered diversions.

• The assumption that the volume diverted under licensed entitlements in the Bunyip, Maribyrnong and Werribee catchments is equal to the entitlement volume is likely to overestimate the actual diversion.
• The assumption that the volume diverted under licensed entitlements in the Yarra catchment is equal to zero is likely to underestimate the actual diversion.

Metered diversions have an uncertainty of +/– 10% due to known errors of meters.

Unmetered estimates of diversion were not quantified.

This item corresponds in part to line item 14.6 Entitled diversion of unregulated surface water flows reported in the 2010 Account. In the 2011 Account, presentation of the line items has changed since the 2010 Account, which has caused the 2009–10 year value to be restated. Line items 14.6.1 Diversion of unregulated flows – Stock and domestic water access entitlement and 14.6.5.6 Diversion of unregulated flows – other lumped holders were merged into a single line item: 17.7 Non-allocated diversions to users.

The restated comparative year volume is 25,745 ML and is the sum of volumes reported at line items 14.6.1 (1,007 ML) and 14.6.5.6 (24,738 ML).