The Melbourne region’s Statement of Changes in Water Assets and Water Liabilities and Statement of Physical Water Flows show an unaccounted volume of 99,308 ML for the groundwater store for 2009–10 (15% of the total water assets). This volume is the amount required to reconcile groundwater inflow volumes against the volume in the groundwater store.
The most likely reason for this unaccounted volume is an overestimation of recharge to groundwater.
The unaccounted-for difference is calculated according to the table below.
| Account | Volume (ML) | |
|---|---|---|
| Opening balance (01 July 2009) groundwater store |
38,438 |
|
| add | Total 15 Groundwater store inflows |
162,466 |
| minus | Total 16 Groundwater store outflows |
44,563 |
| minus | Closing balance (30 June 2010) groundwater store |
38,438 |
| Unaccounted-for difference |
99,308 |