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 geographical area within the catchment containing licensed entitlement that is not covered by these 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.
2024-25 overview
Urban supply
Groundwater supplied to 1 town in the catchment.
Water use
More water was used for consumptive purposes than the previous year.
Climate
Rainfall
Less rainfall was received in the Westernport groundwater catchment in 2024-25 compared to the previous year, being very much below the long-term average across the entire catchment.
Figure 1 displays the rainfall received in 2024-25 compared to the long-term average (1975-2025).
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 level trends reporting in the Accounts does not necessarily represent the status of the resource for management purposes. Groundwater resources are actively managed by rural water corporations. For more detail on management responses, go to Groundwater on the Southern Rural Water
In 2024-25, groundwater level trends for the Corinella GMA and Koo Wee Rup WSPA were declining 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 2024-25, 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 5,550 ML, more than the 3,813 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 2024-25. Total water available under entitlements is calculated as the sum of: opening carryover from the prior year (where available), allocation issued during the reporting year, and the net trade in or out of water, across all entitlements. The level of allocation issued is reduced if there are any restrictions in place.
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 per bore per year.
More information on groundwater use and availability has been detailed in How we account for
In 2024-25, 5,550 ML of water was extracted for consumptive purposes, which was more than the 3,813 ML extracted in the previous year. Of this volume, 4,318 ML was for non-urban (irrigation) use, 110 ML was for urban use, and 1,122 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 |
|
