Changes to water storage reporting
As of 1 July 2010, Melbourne Water has adjusted its water storage reporting to reflect:
Inclusion of water held in Lake Eildon
The table of reservoirs now includes water set aside for Melbourne in Lake Eildon, as part of the Sugarloaf Pipeline Project. This change will more accurately reflect the amount of water available to Melbourne.
Here’s how it works:
- At several points each year, Melbourne receives an allocation of water saved via irrigation upgrades in Northern Victoria
- This water is automatically added to Melbourne’s ‘bottom line’ as it forms part of our available water resources. The total volume of water in storage will increase by this amount, which may appear as a single-day storage gain of up to 2-3% (e.g. from 30% to 32%).
- Transfers from Eildon (via the Sugarloaf Pipeline) into Sugarloaf Reservoir appear as a decrease in the amount of water in Eildon and a corresponding increase in the amount of water in Sugarloaf Reservoir. This is similar to daily transfers between our existing network of 10 dams.
- This storage boost will be gradually ‘drawn down’ as water from Sugarloaf Reservoir is transferred into supply.
A new national water accounting initiative
A new water storage accounting initiative is harmonising the way water authorities across Australia report the capacity of their dams.
To help with this harmonisation, Melbourne Water has changed reporting of its dam capacity from the gigalitre (billion litres) to the nearest megalitre (million litres).
The overall net change in reported capacity is very small – around 0.1%.
This has no impact on the amount of water in storage (already reported to the nearest megalitre).
For example, by measuring capacity to the gigalitre storage levels would be reported as 33.7% full in percentage terms. By measuring capacity to the megalitre storage level is 33.6%. In both instances actual volume is 609,357 ML.
| RESERVOIR | CAPACITY IN ML | CAPACITY IN GL (rounded) | DIFFERENCE IN ML |
|---|---|---|---|
| Thomson | 1,068,000 | 1,068,000 | 0 |
| Cardinia | 286,911 | 287,000 | -89 |
| Upper Yarra | 200,579 | 200,000 | 579 |
| Sugarloaf | 96,253 | 96,000 | 253 |
| Silvan | 40,445 | 40,000 | 445 |
| Tarago | 37,580 | 37,500 | 80 |
| Yan Yean | 30,266 | 30,000 | 266 |
| Greenvale | 26,839 | 27,000 | -161 |
| Maroondah | 22,179 | 22,000 | 179 |
| O’Shanassy | 3,123 | 3,000 | 123 |
| Total system storage | 1,812,175 | 1,810,500 | 1,675 |
What does this table show?
The table above shows the difference in % terms between reporting reservoir levels to the megalitre versus rounding to the gigalitre (i.e. thousand megalitres).