About the area
- The West Port Phillip Bay groundwater catchment extends to the north and west of Melbourne, covering its western suburbs, part of Geelong, and the Bellarine Peninsula.
- The West Port Phillip Bay groundwater catchment contains the Cut Paw Paw Groundwater Management Area (GMA), Lancefield GMA, Merrimu GMA, and Deutgam Water Supply Protection Area (WSPA). The area not covered by GMUs is reported as outside management units.
- Groundwater resources supply licensed entitlements, domestic and stock use, and urban use to Blackwood, Lancefield, and Romsey.
More information on water management and accounting is detailed in Water explained.
2021-22 overview
Urban supply
Groundwater supplied 1 town in the catchment.
Water use
Less water was used for consumptive purposes than the previous year.
Climate
Rainfall
Rainfall in the West Port Phillip Bay groundwater catchment was above average in some areas, similar to the previous year. Rainfall was:
- above average in the Bellarine Peninsula and throughout the central areas of the catchment up to around Ballan to Sunbury
- average in the north of the catchment. It was also average in the south-east, east of Deer Park.
Groundwater level trends
In the accounts, groundwater level trends for groundwater management units (GMUs) have been determined based on monitoring data from key bores in the State Observation Bore Network. Trend determinations are made quarterly by comparing each reading to a previous reading in the same season 5 years prior. That is, a summer record is compared to the summer record from 5 years before to account for seasonality.
Groundwater resources are being actively managed. For more detail on the management responses go to the groundwater on the Southern Rural Water website.
In 2021-22, groundwater level trends in the West Port Phillip Bay groundwater catchment were generally more stable than the previous year.
There are insufficient state observation bores in the Cut Paw Paw GMA to adequately define the groundwater resource or changes to the resource over time.
Table 1: Groundwater level trends, West Port Phillip Bay groundwater catchment
Response to water availability
Groundwater restrictions
In the Deutgam WSPA, licensed diversions were restricted to 50% of the entitlement for 2021-22, the same as the previous year.
Allocations in all other GMUs in the catchment were not restricted.
Entitlements and use
Groundwater licence and use volumes in the West Wimmera groundwater catchment are shown below. Some groundwater licences incorporate domestic and stock use, and in these cases the use is reported in the licensed volume.
The licenced volume used under entitlements must not exceed the volume made available to individual licensed entitlement holders. We report on compliance in the GMU local report and the Statewide groundwater .
Water used
Use in the West Port Phillip Bay groundwater catchment was 2,763 ML, less than 3,251 ML in the previous year.
Entitlement volumes
Rights to water in the West Port Phillip Bay groundwater catchment are shown below.
Table 2: Groundwater entitlements at 30 June, West Port Phillip Bay groundwater catchment
Available water and use
The table below shows the total water available and used under entitlements, and estimated domestic and stock use in 2021-22. Total water available under entitlements is the sum of: opening carryover, allocation issued and the net trade in or out of water.
Estimated domestic and stock use is calculated based on an assumed usage per registered bore per year. In this catchment 1.5 ML usage per bore per year is assumed.
More information on groundwater use and availability has been detailed in the How do we account for section.
In 2021-22, 2,763 ML of water was extracted for consumptive purposes, which was less than the 3,251 ML extracted in the previous year. Of this volume, 1,153 ML was for non-urban (irrigation) use, 47 ML was for urban use, and 1,563 ML was estimated to be for domestic and stock use.
Table 3: Groundwater availability and use, West Port Phillip Bay groundwater catchment
Management responsibilities
Management of water in the West Port Phillip Bay groundwater catchment is undertaken by Southern Rural Water.
| Authority | Management responsibilities |
|---|---|
| Southern Rural Water |
|
