Murray–Darling Basin: Water accounting policies
- Introduction
- Recognition of water assets and water liabilities
- Recognition of changes in water assets and water liabilities
- Restatement of comparative year information
- Transactions within the region
- Reporting of water trade
- Reporting of external transfers
- Level of reporting in case of bulk entitlements in Victoria
Introduction
The information presented in the Murray–Darling Basin region water accounting report is based on agreements between the Bureau of Meteorology (the Bureau) and:
- the Murray–Darling Basin Authority (MDBA)
- Snowy Hydro Limited.
This report has been prepared using an accrual basis of water accounting, with the exception of the physical water flow information. The water attribute being quantified is volume, and the unit of account is megalitres (ML). Where a reported volume is negative, it is shown in brackets. The applicable reporting period is from 1 July 2014 to 30 June 2015. The surface water diversion volume reported in 'Region overview' and 'Water access and use' are net volume. Reported surface water diversion volume also excludes interceptions (plantations and run-off dams). Volumes reported in all other sections of this report are the gross volume for the region.
Recognition of water assets and water liabilities
Only water that is held or managed by the jurisdictional licensing authority and from which future benefit can be derived by stakeholders of the region is identified as a water asset.
Water liabilities are constituted by present commitments to supply water, the discharge of which is expected to result in a decrease of the region's water assets or an increase in another water commitment to supply water.
Provided its volume can be quantified in a way that is complete, neutral, and free from material error, the volume of the water asset or water liability is recognised in the Statement of Water Assets and Water Liabilities.
Water held in storages that has already been abstracted from the entitlement system (e.g. farm dams) is deemed not to be part of the region (regardless of the storage's size or connection to the system). This is because the attendant water right has already been exercised.
The volume of groundwater assets included in the water accounting statements has been recognised as the long-term estimates of volumes for extraction (including New South Wales supplementary access licences for the specific year) plus basic landowner right of groundwater, representing the extractable portion that is required under the Australian Water Accounting Standard 1.
Recognition of changes in water assets and water liabilities
The increases and decreases to the water assets and water liabilities reported consist only of changes that can be quantified in a way that is complete, neutral, and free from material error. These volumes are reported in the Statement of Changes in Water Assets and Water Liabilities or the Statement of Water Flows.
Precipitation and evaporation are recognised on storage surfaces and only for major rivers within the region. These include storages, lakes, weirs, and locks in the regulated and unregulated rivers. It does not represent all precipitation, evaporation and evapotranspiration within the region (notably, these processes occurring from the landscape are not captured).
The portion of runoff from landscape that flows into the surface water store is quantified and recognised. This runoff includes precipitation captured in the catchment less estimated evaporation and seepage and is recorded as Runoff.
Allocations announced on regulated entitlements have been recognised as increases in water liabilities. Note that the definition of regulated or unregulated entitlements for the purpose of the National Water Account (refer to 'Glossary') may be different to the meaning applied by the jurisdiction. Please refer to the Water rights, entitlements, allocations and restrictions for more information on the allocations.
The volume of water that returns after urban use, recorded as Discharge from urban water supply system, meets the identification criteria as an increase to water assets; wherever it could be quantified accurately, it is recognised in the Statement of Changes in Water Assets and Water Liabilities and Statement of Water Flows, and further information is provided in the Notes.
Other groundwater increases and Other groundwater decreases do not represent any physical groundwater flow. The volumes provided represent the change of the long-term estimates of volumes for extraction between the reporting year and the previous year. These changes were as a result of implementation of new water sharing plans, abolition of existing plans, or changes made to New South Wales supplementary access licences. Both the Statement of Changes in Water Assets and Water Liabilities and Statement of Water Flows include Other groundwater increases and Other groundwater decreases, and more information is provided in the Notes.
Restatement of comparative year information
In accordance with the Australian Water Accounting Standard 1, comparative year volumes must be restated in the statements if there is a prior period error or a change in item presentation. Comparative year volumes are not required to be restated if there is a change in scope or methodology or subsequent data availability for the quantification of a item.
The following comparative year volume in the water accounting statements was restated from the 2014 Account.
| Account item | Revised 2014 volume in 2015 Account (ML) | Volume reported in 2014 Account (ML) | Difference (ML) |
| Changes in presentation | |||
| Surface water allocation remaining: environmental purposes | 690,064 | 0 | 690,064 |
| Surface water allocation: environmental purposes | 1,794,054 | 0 | 1,794,054 |
| Surface water allocated diversion: environmental purposes | 1,549,266 | 0 | 1,549,266 |
| Surface water adjustment and forfeiture: environmental purposes | (445,276) | 0 | (445,276) |
| Surface water non-allocated diversion: environmental purposes | 53,219 | 0 | 53,219 |
| Surface water non-allocated diversion: individual users | 1,283,873 | 1,337,092 | (53,219) |
| Groundwater allocation: individual users | 2,161,986 | 2,197,732 | (35,746) |
| Groundwater allocated extractions: individual users | 1,114,458 | 1,120,132 | (5,674) |
| Groundwater allocation remaining: environmental purposes | 99 | 0 | 99 |
| Groundwater allocation: environmental purposes | 35,746 | 0 | 35,746 |
| Groundwater allocated extractions: environmental purposes | 5,674 | 0 | 5,674 |
| Groundwater adjustment and forfeiture: environmental purposes | 29,973 | 0 | 29,973 |
| Discharge: urban supply system | 0 | 32,551 | (32,551) |
| Discharge: wastewater system | 32,551 | 0 | 32,551 |
| Changes in presentation and prior period errors | |||
| Surface water allocation remaining: individual users | 2,567,603 | 3,024,280 | (456,677) |
| Surface water allocation: individual users | 5,810,236 | 6,918,972 | (1,108,736) |
| Surface water allocated diversion: individual users | 7,185,833 | 7,565,617 | (379,784) |
| Surface water adjustment and forfeiture: individual users | 403,191 | 675,466 | (272,275) |
| Groundwater allocation remaining: individual users | 2,341 | 2,132 | 209 |
| Groundwater adjustment and forfeiture: individual users | 1,047,591 | 1,077,872 | (30,281) |
| Changes due to prior period errors | |||
| Surface water allocation: urban system | 523,094 | 520,674 | 2,420 |
| Surface water allocated diversion: urban system | 327,390 | 328,452 | (1,062) |
| Surface water adjustment and forfeiture: urban system | 195,704 | 192,222 | 3,482 |
| Return flow: environmental purposes | 64,200 | 0 | 64,200 |
| Other groundwater assets | 3,262,640 | 3,089,527 | 173,113 |
| Other groundwater increases | 1,186,688 | 1,013,575 | 173,113 |
| Updated information | |||
| Runoff to surface water | 16,374,418 | 20,739,830 | (4,365,412) |
| Other reasons | |||
| River and floodplain losses | 7,088,015 | 12,556,178 | (5,468,163) |
Except for two items, restatements due to changes in presentation have been made to distinguish environmental information from consumptive water supply information. The changes in presentation to the remaining two items 'discharge: urban supply system' and 'discharge: wastewater system' have separated water flows from the urban water supply system from flows from the wastewater system to provide clearer information to users of the National Water Account.
Restatements due to a combination of changes in presentation and prior period errors have been made to distinguish environmental information from consumptive water supply information and correct minor data translation errors in the 2014 Account.
Restatements due to prior period errors have been made to correct errors made in data provision and calculations made during the preparation of the 2014 Account.
AWRA-L version 5.0 was used to estimate ‘Runoff’ in the 2015 Account. The volume for this item for the 2013-14 year has been restated due to following reasons:
- AWRA-L version 5.0 has been recognised as a better version than the previous one, and providing runoff volumes for both years from that version allows readers to better compare information.
- To address reporting partner concerns.
River and floodplain losses volume for the 2013–14 year has been restated as a result of an update to the surface water store variables, which are inputs to the water balance calculation for this item.
Transactions within the region
Transactions between water assets and water liabilities within the region (e.g. between the surface water store and the groundwater store) are not reported in the water accounting statements because they do not affect the region's total water assets and water liabilities.
This information is reported in the Water resources and systems note which includes water accounting statements for each water store. These contain internal transactions that were excluded from the consolidated water accounting statements. This ensures that transactions between water assets and water liabilities within the region are still reported.
Reporting of water trade
It is assumed that all water traded (allocation trade) within the Murray–Darling Basin region has been provided to an account holder within the region, even though delivery may be provided via the distribution network to a location outside of the region.
Water trades are not reported in the water accounting statements; however, some water trades result in the conversion of the category and purpose of use, which will affect their classification. It is believed these effects are reflected in relevant information for allocation remaining, allocation announcements, allocation diversion, and forfeiture and adjustments in the water accounting statements.
Information about interstate, inter-valley and intra-valley trade is included in the Water market activity note.
Reporting of external transfers
Transfers of water that occur across the boundaries of the Murray–Darling Basin region and impact on the water assets and water liabilities of the region are reported in the water accounting statements. Information about these transfers is also provided in the 'Water resources' section of the 'Contextual information' (Figure C9) note.
Level of reporting in case of bulk entitlements in Victoria
When water is managed under a bulk entitlement in Victoria (see Water management plans and Water entitlements under 'Contextual information'), the 2015 Account reports at the level of the collective retail water access entitlements issued under the bulk entitlements. This means that the water liabilities identified against the region are the allocations announced on these retail entitlements and for bulk entitlements held for the benefit of the environment. Where a bulk entitlement holder has a claim over water located outside the region, that claim will likewise be identified as a water asset of the region.