About the area
- The Avoca basin includes the Avoca River, small tributaries (such as Strathfillan Creek and Cherry Tree Creek) and minor watercourses which drain internally (such as Tyrrell Creek, which terminates in Lake Tyrrell). The Avoca River flows into the Kerang Lakes at Lake Bael Bael.
- For the purposes of these accounts, the Avoca basin excludes Swan Hill and the Torrumbarry Irrigation Area, which are supplied from the Murray River.
- The narrow section in the south of the basin consists of steep hills while the wider northern end consists of undulating alluvial plains. Average annual rainfall decreases northwards from around 600 mm near Avoca to 200-300 mm at Lake Tyrell in the far north.
- In the north, all land use is grazing and wheat cropping apart from some small areas of forest south of St Arnaud, on the edge of the basin. There are several small swamps and marshes upstream of Kerang.
More information on water management and accounting is detailed in Water explained.
2021-22 overview
Available water
Catchment inflow was higher than the previous year.
Water use
About the same amount of water was used as the previous year.
When compared to the previous year, in 2021-22:
- more rainfall was received and catchment inflows were higher
- licensed diversions from the Avoca River were only restricted for one month, compared to six the previous year
- about the same amount of water was diverted from the basin for consumptive uses.
Climate
Rainfall
In 2021-22, rainfall in the Avoca basin was above average in most areas, much higher than the year before. Rainfall was:
- average only in small pockets north of Lake Tyrrell, west of Kerang, and west of Avoca
- above average everywhere else in the basin.
River basin water balance
In 2021-22, inflows received (13,300 ML) were higher than the previous year (3,789 ML), reflecting the above average rainfall received. Although higher than the previous year, inflows were very-much below the average of 87,100 ML (15% of the long-term average).
In 2021-22, 1,203 ML of water was diverted for consumptive uses: town, domestic and stock, irrigation and commercial supply, about the same as the 1,138 ML diverted in the previous year.
Water balance table
The table below shows the total volumes of water available and supplied from water resources in the Avoca basin in 2021-22.
Table 1: Water balance, Avoca basin
Catchment inflow
Catchment inflow represents the volume of water flowing into the waterways of a basin. It is calculated to be the difference between the total outflows and the known inflows.
In 2021-22, 5,373 ML outflowed to the terminal lakes in the basin (compared to 6 ML in the previous year).
Below average inflows received
Catchment inflow was 15% of the long-term average annual volume of 87,100 ML.
Higher inflows received
More inflows received than in the previous year (4% of the long-term average in 2020-21).
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 now 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 Highland and Grampians Wimmera Mallee .
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, Avoca basin
Entitlements and compliance
Entitlements provide the basis for how water is shared in the basin.
Entitlement volumes
Rights to water in the Avoca basin are shown in table 3 below.
Entitlement volumes represent a maximum volume 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 varies. The rules for allocating water under an entitlement can differ between entitlements and systems. This affects the ability and likelihood of water being taken in a particular year.
Table 3: Annual entitlement volumes, Avoca 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 202122. The volume includes seasonal allocations and net trade into the basin.
Water taken
There was 641 ML used in 2021-22, more than the year before (545 ML).
Restrictions on licensed diversions from unregulated rivers
In 2021-22 licensed diversions from the Avoca River were only banned for one month (July 2021). This is compared to the previous year when streams were restricted from July 2020 to January 2021.
Available water and take table
This table shows the volume of available water and the volume taken under entitlements in 2021-22.
More information on available water and take has been detailed in the How do we account for surface section on the How do we account for water page.
In 2021-22, more water was taken under entitlements than the previous year.
Table 4: Available water and take, Avoca basin
Compliance
Compliance against water entitlements is reported for this basin in three areas
- entitlement issued: the volume of entitlements issued in a basin does not exceed formal caps or has not increased without appropriate approvals
- water taken: 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: 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 (641 ML) was within the volume available for the year (7,736 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 Avoca basin, so no active environmental watering occurs.
However, important sites and environmental values in the Avoca basin that depend on water for the environment include:
- the Avoca River, with red gums and a floodplain system in the lower Avoca and grassy woodland in the upper Avoca.
- the lower Avoca grasslands, a unique, largely intact mosaic of floodplain associated with grassland and grassy woodland communities and significant flora and fauna values.
Environmental Water Reserve:
In 2021-22 water for the environment in the Avoca 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
- 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 Avoca basin is undertaken by various parties
| Authority | Management responsibilities |
|---|---|
| Central Highlands Water |
|
| GWMWater |
|
| Goulburn-Murray Water |
|
| North Central Catchment Management Authority |
|
| Distribution system | 2021-22 (ML) | 2020-21 (ML) |
|---|---|---|
| Amphitheatre | 9 | 9 |
| Avoca | 21 | 19 |
