Melbourne
9.9 Discharge from urban water system
Supporting information
The volume presented (26,243 ML) represents the treated wastewater discharged to surface water from Western Water's recycled water plants (RWPs) and Yarra Valley Water's local treatment plants (LTPs), and recycled water provided from the Melbourne Water Western Treatment Plant as environmental flows to the Lake Borrie wetlands.
The breakdown of treated wastewater discharged to surface water in the Melbourne region during the 2012–13 year is presented in the following table.
| Authority | Discharge location | Volume (ML) |
| Western Water | Bacchus Marsh RWP to Land lot/lagoon | 141 |
| Gisborne RWP to Jacksons Creek | 488 | |
| Melton RWP to Werribee River | 878 | |
| Riddells Creek RWP to Riddells Creek | 97 | |
| Romsey RWP to Deep Creek | 280 | |
| Sunbury RWP to Jacksons Creek | 1,256 | |
| Subtotal for Western Water | 3,140 | |
| Yarra Valley Water | Brushy Creek LTP to Brushy Creek | 3,245 |
| Craigieburn LTP to Merri Creek | 395 | |
| Healesville LTP to Yarra River | 319 | |
| Upper Yarra LTP to Yarra River | 739 | |
| Lilydale LTP to Olinda Creek | 1,767 | |
| Monbulk LTP to Sassafras Creek | 18 | |
| Wallan LTP to Merri Creek | 204 | |
| Subtotal for Yarra Valley Water | 6,687 | |
| Melbourne Water | Recycled water to Lake Borrie wetlands |
16,416 |
| Total | 26,243 | |
Quantification approach
Melbourne Water
Data source
Supervisory control and data acquisition (SCADA) database.
Provided by
Melbourne Water.
Method
Water recycled and used for conservation flows is metered using an ultrasonic level transmitter. This recycled water is measured by Melbourne Water before being discharged to the Lake Borrie wetlands (Ramsar-listed).
Assumptions, limitations, caveats and approximations
Data are logged daily and reported quarterly, and thus metering periods align with the reporting year.
Uncertainty information
Ultrasonic level transmitters are used to measure flows and are assumed to have an accuracy of +/–5 to +/–10%.
Western Water
Data source
RWP data.
Provided by
Western Water.
Method
Meters are located at the outlet of the treatment plants and are read daily by the treatment plant operators.
Assumptions, limitations, caveats and approximations
Excludes discharge at Woodend RWP to Five Mile Creek, as this is not located within the Melbourne region.
Uncertainty information
The uncertainty is estimated to be +/– 5% based on meter specifications.
Yarra Valley Water
Data source
BI reporting system, treatment plant, and trade waste dashboard and Flow and reuse summary report.
Provided by
Yarra Valley Water.
Method
Meters measuring the volume of treated wastewater discharged from local treatment plants to surface water are read daily.
Assumptions, limitations, caveats and approximations
Nil.
Uncertainty information
The uncertainty is estimated to be +/– 5% based on meter specifications.