About the area
The Westernport groundwater catchment is in south-eastern Victoria, and it takes in the area around and to the north-east of Western Port.
The Westernport groundwater catchment contains the Corinella groundwater management area (GMA), and Koo Wee Rup water supply protection area (WSPA). The area not covered by is reported as outside management units.
The Koo Wee Rup WSPA extends into the East Port Phillip Bay groundwater catchment.
Groundwater resources within the catchment supply licensed entitlements, domestic and stock use, and urban use to Corinella, Grantville, and Lang Lang.
More information on water management and accounting is detailed in Water explained.
2023-24 overview
Urban supply
Groundwater supplied to 1 town in the catchment.
Water use
Water used for consumptive purposes was similar to the previous year.
Climate
Rainfall
Less rainfall was received in the Westernport groundwater catchment in 2023-24 compared to the previous year, ranging from close to very much below the long-term average across the catchment. Rainfall was:
- average across the northern third of the catchment
- below average in a band across the centre of the catchment ranging from Pearcedale to Poowong and Candowie Reservoir, and the eastern portion of French Island
- very much below in southern parts of the catchment encompassing Mornington Peninsula, Phillip Island, San Remo and the western portion of French Island.
Figure 1 displays the rainfall received in 2023-24 compared to the long-term average (1975-2024).
Figure 1: Rainfall deciles, Westernport groundwater catchment
Sourced from the Australian Bureau of Meteorology
Groundwater level trends
In the Accounts, groundwater level trends for groundwater management units (GMUs) have been determined by 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; for example, a summer record is compared to the summer record from 5 years earlier to account for seasonality. These trends are shown in Table 1 below.
Groundwater resources are being actively managed. For more detail on management responses, go to on the Southern Rural Water website.
In 2023-24, groundwater level trends for the Corinella GMA and Koo Wee Rup WSPA were rising towards the end of the year.
Table 1: Groundwater level trends, Westernport groundwater catchment
Response to water availability
Groundwater restrictions
There were no restrictions on licensed groundwater use in 2023-24, the same as previous year.
Entitlements and use
Groundwater licence and use volumes in the Westernport groundwater catchment are shown below. Domestic and stock use does not require a licence, so in the Groundwater availability and take table (Table 3), these rows only report water taken.
The licensed volume used under entitlements must not exceed the volume made available to individual licensed entitlement holders. We report on compliance in the GMU local reports and in the Statewide groundwater summary.
Water used
Use in the Westernport groundwater catchment was 3,813 ML, similar to the 4,115 ML used in the previous year.
Entitlement volumes
Rights to water in the Westernport groundwater catchment are shown below.
Table 2: Groundwater entitlements at 30 June, Westernport groundwater catchment
Available water and take
The table below shows the total water available and taken under entitlements, and estimated domestic and stock use in 2023-24. 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, the assumed usage is 1.5 ML usage per bore per year.
More information on groundwater use and availability has been detailed in How we account for
In 2023-24, 3,813 ML of water was extracted for consumptive purposes, which was similar to the 4,115 ML extracted in the previous year. Of this volume, 2,656 ML was for non-urban (irrigation) use, 49 ML was for urban use, and 1,108 ML was estimated to be for domestic and stock use.
Table 3: Groundwater availability and take, Westernport groundwater catchment
Management responsibilities
Management of water in the Westernport groundwater catchment is undertaken by Southern Rural Water.
| Authority | Management responsibilities |
|---|---|
| Southern Rural Water |
|
