About the area
The Hopkins basin is in south-western Victoria. The 2 major rivers within the basin are the Merri River and the Hopkins River.
The basin is predominantly flat terrain, except for low rolling hills in the north that form the headwaters of the Hopkins River and Fiery Creek. The basin is largely cleared and used for agriculture.
Average annual rainfall in the basin ranges from 400-900 mm.
More information on water management and accounting is detailed in Water explained.
2023-24 overview
Available water
Catchment inflow was lower than the previous year.
Licensed diversion restrictions
There were more restrictions on licensed diversions than the previous year.
Water use
Less water was diverted for consumptive purposes than the previous year.
When compared to the previous year, in 2023-24:
- less rainfall was received, and catchment inflows were much lower
- there were more restrictions on licensed diversions from streams
- less water was diverted from the basin for consumptive uses.
Climate
Rainfall
In 2023-24, rainfall across the entire Hopkins basin was lower than the previous year. Rainfall was:
- lowest on record in most of the basin, from Wickliffe down to the coast, covering Warrnambool, Terang, Mortlake, Lake Bolac and Koroit and a very small area in the north near Beaufort
- very much below average in most of the north, covering Willaura, Skipton, Ararat and Ballarat.
Figure 1 displays the rainfall received in 2023-24 compared to the long-term average (1975-2024).
Figure 1: Rainfall deciles, Hopkins basin
Sourced from the Australian Bureau of Meteorology
River basin water balance
This section describes the known and estimated inflows, outflows and change of storage volumes in the basin.
More detail on catchment inflows, diversions and small catchment dams can be found in the sections below the water balance.
Of the total inflows, 93% flowed out into the ocean in 2023-24.
Water balance table
The table below shows the total volumes of water available and supplied from water resources in the Hopkins basin in 2023-24.
Table 1: Water balance, Hopkins basin
Inflows
Catchment inflow
Catchment inflow represents the volume of water flowing into the waterways of a basin. It is calculated as the total outflows and change in storage minus the known inflows. The long-term average inflow presented has been updated from the previous Victorian Water Accounts, as detailed in Water Explained. The updated long-term average inflow has been applied to this year and the previous year’s volume in this report.
Below average inflows of 126,763 ML were received (39% of the long-term average of 328,000 ML), much less than the previous year (288% of the long-term average).
Below average inflow received
Catchment inflow was 39% of the long-term average of 328,000 ML.
Less water received than the previous year
This was much less than the previous year (288% of the long-term average).
Wastewater treatment plants
Water treated at wastewater treatment plants can be used to supplement water available in the basin. Water discharged to waterways from treatment plants is included as an inflow to the water balance.
Information on treatment plants is reported in the water supply local reports for the water corporation responsible for managing the plant.
In this basin, wastewater treatment plants are managed by Central Highlands Water, Grampians Wimmera Mallee Water and Wannon Water.
Outflows
Diversions
In 2023-24, 4,967 ML of water was diverted for consumptive uses: town, domestic and stock, irrigation and commercial supply. This is less than the previous year (12,063 ML). While a decrease in use was reported, urban and licensed diversions were higher than the previous year. The overall decrease in consumptive use was due to the 8,046 ML decrease in the estimate of small catchment dam use volume.
Small catchment dams
Water harvested, used, and lost by small catchment dams (farm dams) is included in the water balance.
Table 2: Small catchment dams, Hopkins basin
Entitlements and compliance
Entitlements provide the basis for how water is shared in the basin.
Grampians Wimmera Mallee Water’s bulk entitlement to the Hopkins basin (Willaura, Elmhurst and Buangor) is reported in the Wimmera basin, as it covers water sourced from both basins, most of which is sourced from the Wimmera basin.
Entitlement volumes
Rights to water in the Hopkins basin are shown in Table 3.
Entitlement volumes represent a maximum volume of water that can be taken in a one-year period. The volume available in a particular year is dependent on the rules for allocating water set out in the entitlement and the seasonal conditions in that year, which can vary. The rules for allocating water under an entitlement differ between entitlements and systems. This affects the ability and likelihood of water being taken in a particular year.
Table 3: Annual entitlement volumes at 30 June, Hopkins basin
Available water and take under entitlements
Total water available under entitlements represents the volume of water that was available to be taken by entitlement holders in 2023-24. The volume includes seasonal allocations and net trade into the basin.
Water taken
There was 2,895 ML taken under entitlements in 2023-24, less than the previous year (3,946 ML).
Restrictions on licensed diversions from streams
- In 2023-24, all stream sections had restrictions or bans in place from January to April 2024. Zone B of the Merri River had a Stage 1 restriction in place for the entirety of 2023-24.
- During the previous year, the Merri River had Stage 1 restrictions in place between January 2023 to June 2023 for zone B, and between January 2023 to March 2023 for zone A.
Available water and take table
This table shows the volume of available water and the volume taken under entitlements in 2023-24.
More information on available water and take has been detailed in How we account for surface water.
In 2023-24, less water was taken under entitlements than the previous year.
Table 4: Available water and take under entitlements, Hopkins basin
Compliance
Compliance against water entitlements is reported for this basin in 3 areas:
- entitlement issued: that the volume of entitlements issued in a basin does not exceed formal caps, and has not increased without appropriate approvals
- water taken: that the volume of water taken during the year does not exceed the volume considered to be available for consumptive and/or in-stream use during that year
- bulk entitlement provisions: that holders of entitlements do not breach any provisions that are documented in their bulk entitlement orders.
Total entitlement volume
There was no net increase in the total entitlement volume from the previous year.
Total volume diverted
The total volume diverted under entitlements (2,895 ML) was within the volume available for the year (17,949 ML).
Individual bulk entitlements
No individual bulk entitlement holder took more than the annual volume made available to them.
Exceptions to compliance
Individual bulk entitlement holders complied with all provisions in their entitlements.
Water for the environment
Environmental watering sites
There are no environmental entitlements in the Hopkins basin, so no active environmental watering occurs. However, important sites in the Hopkins basin that depend on water for the environment include:
- coastal salt marsh wetlands and the wetlands associated with the Merri River estuary
- the Hopkins River, a major waterway draining the eastern part of the region and entering the Southern Ocean at Warrnambool
- Hopkins estuary, the Merri River and Fiery Creek
- Brucknell Creek and Deep Creek, which provide important fish habitat for species including the Australian grayling and river blackfish
- Mt Emu Creek, which contains reaches with relatively intact remnant riparian vegetation and deep, permanent pools providing drought refuge for threatened species.
Environmental water reserve
In 2023-24, water for the environment in the Hopkins basin comprised:
- water set aside for the environment through the operation of passing flow conditions:
- on consumptive bulk entitlements held by Central Highlands Water
- on licensed diversions, particularly for Cudgee and Mt Emu creeks
- all other water in the basin not allocated for consumptive uses: this water also provides social, recreational and cultural benefits.
Management responsibilities
Management of water in the Hopkins basin is undertaken by various parties
| Authority | Management responsibilities |
|---|---|
| Central Highlands Water |
|
| Glenelg Hopkins Catchment Management Authority |
|
| Grampians Wimmera Mallee Water |
|
| Southern Rural Water |
|
| Wannon Water |
|
| Water supply system | 2022-23 (ML) | 2023-24 (ML) |
|---|---|---|
| Beaufort & Raglan System | 152 | 186 |
