18.11 Entitled extraction of allocated groundwater to users

Supporting information

The volume presented in the water accounting statements (13,173 ML) represents metered extraction and estimated stock and domestic extraction under groundwater entitlements in groundwater management units in the Melbourne region.

The following table shows the breakdown of groundwater volumes extracted from groundwater management units in the Melbourne region during the 2011–12 year.

Groundwater allocation extraction in the Melbourne region during the 2011–12 year
Groundwater management unit Metered extraction (ML) Estimated S&D extraction (ML) Usage of allocation %
Cut Paw Paw Groundwater Management Area (GMA)
84 59 24%
Deutgam Water Supply Protection Area (WSPA)—groundwater 979 294 23%
Frankston GMA 119 201 16%
Koo Wee Rup WSPA—groundwater 1,921 1,877 26%
Lancefield GMA
106 108 17%
Merrimu GMA 145 26 36%
Moorabbin GMA 873 569 43%
Nepean GMA 3,152 2,249 51%
Wandin Yallock WSPA—groundwater 285 126 13%
Subtotal 7,664 5,509 32%
Total extraction   13,173  

Quantification approach

Data source

Victorian Water Register.

Provided by

Victorian Department of Environment and Primary Industries.


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

Metered extractions

Southern Rural Water meter groundwater extractions and submit this data to the Victorian Water Register. Metered extraction volumes were obtained from the Victorian Water Register for all groundwater management units for the 2011–12 year.

Un-metered estimated extractions

Stock and domestic entitlements are not currently metered in Victoria. Extraction was estimated by multiplying a usage factor between 0 and 2 ML by the number of stock and domestic bores in the region:

  • A factor of zero estimates that no extraction occurred
  • A factor of two estimates that the full entitlement was extracted.

During the 2011–12 year, a usage factor of 1.5 was applied to all stock and domestic entitlements, with the exception of Nepean GMA where a usage factor of 1 was applied.

Assumptions, limitations, caveats and approximations

  • Not all groundwater bores are metered. Bores that were not metered were not used or did not fall within the threshold of Southern Rural Water's metering program. The number of non-metered bores is estimated to be 10-20% of the total bores in the area. The volume of extraction from bores that are not metered is not considered to have a material impact on this water accounting report.
  • A broad assumption is made to estimate stock and domestic extraction. It is unlikely that all extraction matches the assumption. In a wet year, the estimate is likely to overestimate the volume of stock and domestic extraction.

Uncertainty information

  • Metered data has an uncertainty of +/–5% based on meter specifications.
  • Estimated data has an uncertainty of +/–100% based on the broad assumptions applied.

Comparative year

In the 2011 Account, it was not possible to separate urban and non-urban entitlements to groundwater. Therefore, the volume of groundwater extracted for all groundwater entitlements was reported at line item 18.11 'Groundwater allocation extraction'.

In the 2012 Account, data provided to the Bureau has enabled non-urban entitlements to groundwater to be reported separately in the Melbourne Account.

Consequently, the volume has been restated from 10,196 ML (as published in the 2011 Account) to 10,184 ML.

Comparative year information for entitled extraction of allocated groundwater to users
Groundwater management unit 2012 Account volume for the 2010–11 year (ML)
2011 Account volume for the 2010–11 year (ML)
Cut Paw Paw GMA
30 30
Deutgam WSPA—groundwater 262 262
Frankston GMA 279 279
Koo Wee Rup WSPA— groundwater 3,884 3,888
Lancefield GMA
157 165
Merrimu GMA
198 198
Moorabbin GMA
1,100 1,100
Nepean GMA
3,953 3,953
Wandin Yallock WSPA— groundwater 321 321
Total 10,184 10,196