About the area
The Tarwin groundwater catchment is in south-eastern Victoria. Bass Strait forms the catchment's southern boundary.
The Tarwin groundwater catchment contains the Leongatha groundwater management area (GMA) and Tarwin GMA. The area not covered by these is reported as outside management units.
Groundwater resources within the catchment supply licensed entitlements, domestic and stock use, and urban use to Leongatha.
More information on water management and accounting is detailed in Water explained.
2022-23 overview
Water use
Less water was used for consumptive purposes than the previous year.
Climate
Rainfall
More rainfall was received in the Tarwin groundwater catchment in 2022-23 compared to the previous year, being above the long-term average across most of the catchment. Rainfall was:
- very much above average along the north-west edge of the catchment
- above average across the central regions of the catchment from Wonthaggi and Miraboo North south to Corner Inlet
- average in areas around Waratah Bay and across Wilsons Promontory.
Figure 1 displays the rainfall received in 2022-23 compared to the long-term average (1975-2023).
Figure 1: Rainfall deciles, Tarwin 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.
Groundwater resources are being actively managed. For more detail on management responses, go to on the Southern Rural Water website.
In 2022-23, groundwater level trends for the Leongatha and Tarwin GMAs were rising and stable, respectively towards the end of the year.
Table 1: Groundwater level trends, Tarwin groundwater catchment
Entitlements and use
Groundwater licence and use volumes in the Tarwin groundwater catchment are shown below. Domestic and stock use does not require a licence, so in the Groundwater availability and use table, 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 Statewide groundwater.
Water used
Use in the Tarwin groundwater catchment was 648 ML, less than the 749 ML used in the previous year.
Entitlement volumes
Rights to water in the Tarwin groundwater catchment are shown below.
Table 2: Groundwater entitlements at 30 June, Tarwin 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 2022-23. 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 2022-23, 648 ML of water was extracted for consumptive purposes, which was less than the 749 ML extracted in the previous year. Of this volume, 38 ML was for non-urban (irrigation) use, and 610 ML was estimated to be for domestic and stock use.
There were no restrictions on use in the Tarwin groundwater catchment in 2022-23.
Table 3: Groundwater availability and use, Tarwin groundwater catchment
Management responsibilities
Management of water in the Tarwin groundwater catchment is undertaken by Southern Rural Water.
| Authority | Management responsibilities |
|---|---|
| Southern Rural Water |
|
